Plurality of flaky magnetic metal particles, pressed powder material, and rotating electric machine

ABSTRACT

Provided is a plurality of flaky magnetic metal particles of the embodiments, each flaky magnetic metal particle having a flat surface provided with either or both of a plurality of concavities and a plurality of convexities arranged in a first direction, each concavity or convexity having a width of 0.1 μm or more, a length of 1 μm or more, and an aspect ratio of 2 or higher; and at least one first element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni), the flaky magnetic metal particles having an average thickness of between 10 nm and 100 μm inclusive and an average aspect ratio of between 5 and 10,000 inclusive.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2017-047116, filed on Mar. 13, 2017, theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a plurality of flakymagnetic metal particles, a pressed powder material, and a rotatingelectric machine.

BACKGROUND

Currently, soft magnetic materials are applied to various systems anddevices, such as rotating electric machines (for example, motors andgenerators), potential transformers, inductors, transformers, magneticinks, and antenna devices, and thus, soft magnetic materials areregarded as very important materials. In these component parts, the realpart of the magnetic permeability (real part of the relative magneticpermeability), μ′, of a soft magnetic material is utilized. Therefore,in the case of actual use, it is preferable to control μ′ in accordancewith the working frequency band. Furthermore, in order to realize ahighly efficient system, it is preferable to use a material having aloss that is as low as possible. That is, it is preferable that theimaginary part of the magnetic permeability (imaginary part of therelative magnetic permeability), μ″ (corresponding to a loss), isminimized as far as possible. In regard to the loss, the loss factor,tan δ (=μ″/μ′×100(%)), serves as a criterion, and as μ″ becomes smallerrelative to μ′, the loss factor tan δ becomes smaller, which ispreferable. In order to attain such conditions, it is preferable to makethe core loss for the conditions of actual operation small, that is tosay, it is preferable to make the eddy current loss, hysteresis loss,ferromagnetic resonance loss, and residual loss (other losses) as smallas possible. In order to make the eddy current loss small, it iseffective to increase the electrical resistance, or decrease the sizesof metal parts, or finely divide the magnetic domain structure. In orderto make the hysteresis loss small, it is effective to reduce coercivityor increase the saturation magnetization. In order to make theferromagnetic resonance loss small, it is effective to make theferromagnetic resonance frequency higher by increasing the anisotropicmagnetic field of the material. Furthermore, in recent years, sincethere is an increasing demand for handling of high electric power, it isrequired that losses be small, particularly under the operationconditions in which the effective magnetic field applied to the materialis large, such as high current and high voltage. To attain this end, itis preferable that the saturation magnetization of a soft magneticmaterial is as large as possible so as not to cause magnetic saturation.Furthermore, in recent years, since size reduction of equipment isenabled by frequency increment, increase of the working frequency bandthat is utilized in systems and device equipment is underway, and thereis an urgent need for the development of a magnetic material having highmagnetic permeability and low losses at high frequency and havingexcellent characteristics.

Furthermore, in recent years, due to the heightened awareness of theissues on energy saving and environmental issues, there is a demand toincrease the efficiency of systems as high as possible. Particularly,since motor systems are responsible for the greater portion of electricpower consumption in the world, efficiency enhancement of motors is veryimportant. Above all, a core and the like that constitute a motor areformed from soft magnetic materials, and it is requested to increase themagnetic permeability or saturation magnetization of soft magneticmaterials as high as possible, or to make the losses as low as possible.Furthermore, in regard to the magnetic wedge that is used in somemotors, there is a demand for minimizing losses as far as possible.There is the same demand also for systems using transformers. In motors,transformers and the like, the demand for size reduction is also high,along with efficiency enhancement. In order to realize size reduction,it is essential to maximize the magnetic permeability and saturationmagnetization of the soft magnetic material as far as possible.Furthermore, in order to also prevent magnetic saturation, it isimportant to make saturation magnetization as high as possible.Moreover, the need for increasing the operation frequency of systems isalso high, and thus, there is a demand to develop a material having lowlosses in high frequency bands.

Soft magnetic materials having high magnetic permeability and low lossesare also used in inductance elements, antenna devices and the like, andamong them, in recent years, attention has been paid to the applicationof soft magnetic materials particularly in power inductance elementsthat are used in power semiconductor devices. In recent years, theimportance of energy saving and environmental protection has beenactively advocated, and there have been demands for a reduction of theamount of CO₂ emission and reduction of the dependency on fossil fuels.As the result, development of electric cars or hybrid cars thatsubstitute gasoline cars is in active progress. Furthermore,technologies for utilizing natural energy such as solar power generationand wind power generation are regarded as key technologies for an energysaving society, and many developed countries are actively pushing aheadwith the development of technologies for utilizing natural energy.Furthermore, the importance of establishment of home energy managementsystems (HEMS) and building and energy management systems (BEMS), whichcontrol the electric power generated by solar power generation, windpower generation or the like by a smart grid and supply the electricpower to homes, offices and plants at high efficiency, asenvironment-friendly power saving system, has been actively advocated.In such a movement of energy saving, power semiconductor devices play akey role. Power semiconductor devices are semiconductor devices thatcontrol high electric power or energy with high efficiency, and examplesthereof include discrete power semiconductor devices such as aninsulated gate bipolar transistor (IGBT), a metal oxide semiconductorfield effect transistor (MOSFET), a power bipolar transistor and a powerdiode; power supply circuits such as a linear regulator and a switchingregulator; and a large-scale integration (LSI) logic circuit for powermanagement to control the above-mentioned devices. Power semiconductordevices are widely used in all sorts of equipment including electricalappliances, computers, automobiles and railways, and since expansion ofthe supply of these applied apparatuses, and an increase of the mountingratio of power semiconductor devices in these apparatuses can beexpected, a rapid growth in the market for power semiconductor devicesin the future is anticipated. For example, inverters that are installedin many electrical appliances use power semiconductor devices nearly inall parts, and thereby extensive energy saving is made possible.Currently, silicon (Si) occupies a major part in power semiconductordevices; however, for a further increase in efficiency or further sizereduction of equipment, utilizing silicon carbide (SiC) and galliumnitride (GaN) is considered effective. SiC and GaN have larger band gapsand larger breakdown fields than Si, and since the withstand voltage canbe made higher, elements can be made thinner. Therefore, theon-resistance of semiconductor devices can be lowered, and it iseffective for loss reduction and efficiency enhancement. Furthermore,since SiC or GaN has high carrier mobility, the switching frequency canbe made higher, and this is effective for size reduction of elements.Furthermore, since SiC in particular has higher thermal conductivitythan Si, the heat dissipation ability is higher, and operation at hightemperature is enabled. Thus, cooling systems can be simplified, andthis is effective for size reduction. From the viewpoints describedabove, development of SiC and GaN power semiconductor devices isactively in progress. However, in order to realize the development,development of power inductor elements that are used together with powersemiconductor devices, that is, development of soft magnetic materialshaving high magnetic permeability (high magnetic permeability and lowlosses), is indispensable. In this case, regarding the characteristicsrequired from magnetic materials, high magnetic permeability in thedriving frequency bands, low magnetic loss, and high saturationmagnetization that can cope with a large electric current, are needed.In a case in which saturation magnetization is high, it is difficult tocause magnetic saturation even if a high magnetic field is applied, anda decrease in the effective inductance value can be suppressed. As aresult, the direct current superimposition characteristics of the deviceare improved, and the efficiency of the system is increased.

Furthermore, a magnetic material having high magnetic permeability andlow losses at high frequency is expected to be applied to high frequencycommunication equipment devices such as antenna devices. As a methodeffective for size reduction of antennas and power saving, there isavailable a method of using an insulated substrate having high magneticpermeability (high magnetic permeability and low losses) as an antennasubstrate, and performing transmission and reception of electric wavesby dragging the electric waves that should reach an electronic componentor a substrate inside a communication apparatus from antennas into theantenna substrate, without allowing the electric waves to reach theelectronic component or substrate. As a result, size reduction ofantennas and power saving are made possible, and at the same time, theresonance frequency band of the antennas can also be broadened, which ispreferable.

In addition, examples of other characteristics such as high thermalstability, high strength, and high toughness are required when magneticmaterials are incorporated into the various systems and devicesdescribed above. Also, in order for the magnetic materials to be appliedto complicated shapes, a pressed powder is preferable to materialshaving a sheet shape or a ribbon shape. However, generally, in the caseof the pressed powder, it is well known that characteristics such assaturation magnetization, magnetic permeability, losses, strength andtoughness are not so good. Thus, enhancement of characteristics ispreferable.

Next, in regard to conventional soft magnetic materials, the kinds ofthe soft magnetic materials and their problems will be described.

An example of an existing soft magnetic material for systems of 10 kH orless is a silicon steel sheet (FeSi). A silicon steel sheet is amaterial that is employed in most of rotating electric machines thathave been used for a long time and handle large power, and the corematerials of transformers. Highly characterized materials ranging fromnon-oriented silicon steel sheets to grain-oriented silicon steel sheetscan be obtained, and compared to the early stage of discovery, aprogress has been made; however, in recent years, it is considered thatcharacteristics improvement has reached a limit. Regarding thecharacteristics, it is particularly critical to simultaneously satisfyhigh saturation magnetization, high magnetic permeability, and lowlosses. Studies on materials that surpass silicon steel sheets areactively conducted globally, mainly based on the compositions ofamorphous materials and nanocrystalline materials; however, a materialcomposition that surpasses silicon steel sheets in all aspects has notyet been found. Furthermore, studies also have been conducted on pressedpowders that are applicable to complicated shapes; however, pressedpowders have a defect that they have poor characteristics compared tosheets or ribbons.

Examples of conventional soft magnetic materials for systems of 10 kHzto 100 kHz include SENDUST (Fe—Si—Al), nanocrystalline FINEMET(Fe—Si—B—Cu—Nb), ribbons or pressed powders of Fe-based or Co-basedamorphous glass, and MnZn-based ferrite materials. However, all of thesematerials do not completely satisfy characteristics such as highmagnetic permeability, low losses, high saturation magnetization, highthermal stability, high strength and high toughness, and areinsufficient.

Examples of conventional soft magnetic materials of 100 kHz or higher(MHz frequency band or higher) include NiZn-based ferrites and hexagonalferrites; however, these materials have insufficient magneticcharacteristics at high frequency.

From the circumstances described above, development of a magneticmaterial which has high saturation magnetization, high magneticpermeability, low losses, high thermal stability, and excellentmechanical characteristics, is preferable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating flaky magnetic metalparticles according to a first embodiment of the invention.

FIG. 2 is a schematic diagram illustrating the flaky magnetic metalparticles according to the first embodiment of the invention.

FIG. 3 is a schematic diagram illustrating the desired direction of theeasy magnetization axis of the flaky magnetic metal particles accordingto the first embodiment of the invention.

FIG. 4 is a schematic diagram illustrating the desired direction of theeasy magnetization axis of the flaky magnetic metal particles accordingto the first embodiment of the invention.

FIG. 5 is a schematic diagram illustrating flaky magnetic metalparticles containing extraneous metal particles according to the firstembodiment of the invention.

FIG. 6 is a scanning electron microscopic photograph of the flakymagnetic metal particles according to the first embodiment of theinvention.

FIG. 7 is a scanning electron microscopic photograph of the flakymagnetic metal particles according to the first embodiment of theinvention.

FIG. 8 is a schematic diagram illustrating flaky magnetic metalparticles having small magnetic metal particles according to the firstembodiment of the invention.

FIGS. 9A and 9B are schematic diagrams of the flaky magnetic metalparticles according to a second embodiment of the invention.

FIG. 10 is a schematic diagram illustrating a pressed powder materialaccording to a third embodiment of the invention.

FIG. 11 is a schematic diagram illustrating a method of determining anapproximate first direction according to the third embodiment of theinvention.

FIG. 12 is a schematic diagram illustrating an example of the directionof arrangement (example of the proportion of arrangement) of theapproximate first direction according to the third embodiment of theinvention.

FIG. 13 is an exemplary scanning electron microscopic photograph of thedirection of arrangement of the approximate first direction according tothe third embodiment of the invention.

FIG. 14 is a schematic diagram illustrating the desired directions ofthe approximate first direction and the easy magnetization axisaccording to the third embodiment of the invention.

FIG. 15 is a schematic diagram illustrating the disposition of aninterposed phase according to the third embodiment of the invention.

FIG. 16 is a scanning electron microscopic photograph of flaky magneticmetal particles containing an interposed phase according to the thirdembodiment of the invention.

FIG. 17 is a diagram illustrating the directions obtainable whencoercivity is measured for flaky magnetic metal particles according tothe fourth embodiment of the invention, by changing the direction at aninterval of 22.5° with respect to the angle of 360° within a flatsurface.

FIG. 18 is a diagram illustrating the angle formed by a face parallel tothe flat surface of a flaky magnetic metal particle and a plane surfaceof a pressed powder material according to a sixth embodiment of theinvention.

FIG. 19 is a diagram illustrating the directions obtainable whencoercivity is measured with the plane surface of the pressed powdermaterial according to the sixth embodiment of the invention, by changingthe direction at an interval of 22.5° with respect to the angle of 360°in the plane surface.

FIG. 20 is a diagram illustrating examples of a magnetization curve in adirection in which coercivity has the minimum value and a magnetizationcurve in a direction in which coercivity has the maximum value, within aflat surface of the pressed powder material according to the sixthembodiment of the invention.

FIG. 21 is a diagram illustrating an example of a difference incoercivity on the basis of direction within a flat surface of thepressed powder material according to the sixth embodiment of theinvention.

FIG. 22 is an exemplary conceptual diagram of a motor system accordingto a seventh embodiment of the invention.

FIG. 23 is a schematic diagram illustrating the motor of the seventhembodiment of the invention.

FIG. 24 is a schematic diagram illustrating a motor core according tothe seventh embodiment of the invention.

FIG. 25 is a schematic diagram illustrating the motor core according tothe seventh embodiment of the invention.

FIG. 26 is a schematic diagram illustrating a potential transformer anda transformer according to the seventh embodiment of the invention.

FIG. 27 is a schematic diagram illustrating an inductor according to theseventh embodiment of the invention.

FIG. 28 is a schematic diagram illustrating an inductor according to theseventh embodiment of the invention.

FIG. 29 is a schematic diagram illustrating a generator according to theseventh embodiment of the invention.

FIG. 30 is a conceptual diagram illustrating the relation between thedirection of magnetic flux and the direction of disposition of a pressedpowder material.

DETAILED DESCRIPTION

In the following description, embodiments of the invention will beexplained using the attached drawings. In the diagrams, an identical orsimilar reference numeral will be assigned to identical or similarsites.

First Embodiment

According to the present embodiment, there is provided a plurality offlaky magnetic metal particles, each of the flaky magnetic metalparticles comprising: a flat surface having either or both of aplurality of concavities and a plurality of convexities, the concavitiesand the convexities being arranged in a first direction and each havinga width of 0.1 μm or more, a length of 1 μm or more, and an aspect ratioof 2 or higher; and at least one first element selected from the groupconsisting of iron (Fe), cobalt (Co), and nickel (Ni), the averagethickness of the flaky magnetic metal particles being between 10 nm and100 μm inclusive, and the average aspect ratio being between 5 and10,000 inclusive.

In regard to the thickness and the aspect ratio, average values areemployed in all cases. Specifically, a value obtained by averaging thevalues of ten or more particles is employed.

Flaky magnetic metal particles are flaky particles (or flattenedparticles) having a flaky shape (or a flattened shape).

The average thickness of the flaky magnetic metal particles is between10 nm and 100 μm inclusive. The average thickness is more preferablybetween 10 nm and 1 μm inclusive, and even more preferably between 10 nmand 100 nm inclusive. As a result, when a magnetic field is applied in adirection parallel to the flat surface, the eddy current loss becomessufficiently small, which is preferable. Furthermore, a smallerthickness is preferred because the magnetic moment is confined in adirection parallel to the flat surface, and magnetization is likely toproceed by rotation magnetization, which is preferable. In a case inwhich magnetization proceeds by rotation magnetization, sincemagnetization is likely to proceed reversibly, coercivity is decreased,and the hysteresis loss can be reduced thereby, which is preferable.

The average thickness t is determined by observing the flaky magneticmetal particles by transmission electron microscopy (TEM) or scanningelectron microscopy (SEM). The average aspect ratio of the flakymagnetic metal particles is between 5 and 10,000 inclusive. It isbecause magnetic permeability becomes larger as the result. It is alsobecause the ferromagnetic resonance frequency can be increased, andtherefore, the ferromagnetic resonance loss can be made small.Furthermore, when the aspect ratio is high, the magnetic moment isconfined in a direction parallel to the flat surface, and magnetizationis likely to proceed by rotation magnetization, which is preferable. Ina case in which magnetization proceeds by rotation magnetization, sincemagnetization is likely to proceed reversibly, coercivity becomes small,and the hysteresis loss can be reduced thereby, which is preferable.

The average aspect ratio is defined by the formula: (((a+b)/2)/t), usingthe maximum length a, the minimum length b, and thickness t in the flatsurface. The maximum length a and the minimum length b are determined asfollows. The flat surface is subjected to TEM observation or SEMobservation, a line is drawn in a direction perpendicular to the tangentline at a point on the contour line of the flat surface, and the lengthfrom the line to a point intersecting the contour line on the oppositeside is measured. This process is carried out for all points on thecontour line, and the maximum length a and the minimum length b aredetermined.

FIG. 1 and FIG. 2 are schematic diagrams illustrating the flaky magneticmetal particles of the present embodiment. FIG. 1 is a schematicperspective view of the flaky magnetic metal particles of the presentembodiment. In the upper diagram of FIG. 1, only concavities areprovided, and in the middle diagram of FIG. 1, only convexities areprovided. However, one flaky magnetic metal particle may have bothconcavities and convexities, as shown in the lower diagram of FIG. 1.FIG. 2 is a schematic diagram illustrating the case in which a flakymagnetic metal particle of the present embodiment is viewed from above.The width and length of the concavities or convexities, and the distancebetween concavities or convexities are shown. The aspect ratio of aconcavity or a convexity is the ratio of the length of the major axis tothe length of the minor axis, and in FIG. 1(b), the aspect ratio is theratio of (length of a concavity or a convexity)/(width of a concavity ora convexity). In FIG. 1, concavities 2 a, convexities 2 b, flat surfaces6, and flaky magnetic metal particles 10 are shown.

A flaky magnetic metal particle has, on the flat surface, either or bothof a plurality of concavities and a plurality of convexities that arearranged in a first direction, each of the concavities or theconvexities having a width of 0.1 μm or more, a length of 1 μm or more,and an aspect ratio of 2 or higher. The aspect ratio is defined by theratio of the size in the longitudinal direction to the size in thetransverse direction. That is, in a case in which the length side islarger (longer) than the width, the aspect ratio is defined by the ratioof length to width, and in a case in which the width is larger (longer)than the length, the aspect ratio is defined by the ratio of width tolength. It is more preferable that the length side is larger (longer)than the width, because the flaky magnetic metal particle is likely tohave magnetic uniaxial anisotropy. Furthermore, concavities orconvexities are arranged in the first direction on the flat surface.Here, the phrase “(be) arranged in the first direction” implies thatconcavities or convexities are arranged such that the longer sidebetween the length and the width of the concavities or the convexitiesis parallel to the first direction. Meanwhile, when concavities orconvexities are arranged such that the longer side between the lengthand the width of the concavities or the convexities is within ±30° in adirection parallel to the first direction, it is said that theconcavities or convexities are “arranged in the first direction”. As aresult, the flaky magnetic metal particles are likely to have magneticuniaxial anisotropy in the first direction by a shape magneticanisotropy effect, which is preferable. It is preferable that the flakymagnetic metal particles have magnetic anisotropy in one directionwithin the flat surface, and this will be explained in detail. First, ina case in which the magnetic domain structure of the flaky magneticmetal particles is a multi-domain structure, the magnetization processproceeds by domain wall displacement; however, in this case, coercivityin the easy axis direction within the flat surface becomes lower thanthat in the hard axis direction, and losses (hysteresis loss) aredecreased. Furthermore, magnetic permeability in the easy axis directionbecomes higher than that in the hard axis direction. Furthermore,compared to the case of flaky magnetic metal particles that areisotropic, particularly the coercivity in the easy axis directionbecomes lower in the case of flaky magnetic metal particles havingmagnetic anisotropy, and as a result, losses become smaller, which ispreferable. Also, magnetic permeability becomes high, and it ispreferable. That is, when the flaky magnetic metal particles havemagnetic anisotropy in a direction within the flat surface, magneticcharacteristics are enhanced as compared to an isotropic material.Particularly, magnetic characteristics are superior in the easy axisdirection within the flat surface than in the hard axis direction, whichis preferable. Next, in a case in which the magnetic domain structure ofthe flaky magnetic metal particles is a single domain structure, themagnetization process proceeds by rotation magnetization; however, inthis case, coercivity in the hard axis direction within the flat surfacebecomes lower than that in the easy axis direction, and losses becomesmall. In a case in which magnetization proceeds completely by rotationmagnetization, coercivity becomes zero, and the hysteresis loss becomeszero, which is preferable. Whether magnetization proceeds by domain walldisplacement (domain wall displacement type) or by rotationmagnetization (rotation magnetization type) can be determined on thebasis of whether the magnetic domain structure becomes a multi-domainstructure or a single domain structure. At this time, whether themagnetic domain structure becomes a multi-domain structure or a singledomain structure is determined on the basis of the size (thickness oraspect ratio) of the flaky magnetic metal particles, composition, thecondition of the magnetic interaction between particles, and the like.For example, as the thickness t of the flaky magnetic metal particles issmaller, the magnetic domain structure is more likely to become a singledomain structure, and when the thickness is between 10 nm and 1 μminclusive, and particularly when the thickness is between 10 nm and 100nm inclusive, the magnetic domain structure is likely to become a singledomain structure. Regarding the composition, in a composition havinghigh magnetocrystalline anisotropy, even if the thickness is large, ittends to be easy to maintain a single domain structure. In a compositionhaving low magnetocrystalline anisotropy, if the thickness is not small,it tends to be difficult to maintain a single domain structure. That is,the thickness of the borderline between being a single domain structureor a multi-domain structure varies also depending on the composition.Furthermore, when the flaky magnetic metal particles magneticallyinteract with neighboring particles, and the magnetic domain structureis stabilized, the magnetic domain structure is likely to become asingle domain structure. The determination of whether the magnetizationbehavior is of the domain wall displacement type or of the rotationmagnetization type can be made simply as follows. First, within a planeof the material (a plane that is parallel to the flat surface of a flakymagnetic metal particle), magnetization is analyzed by varying thedirection in which a magnetic field is applied, and two directions inwhich the difference in the magnetization curve becomes the largest (atthis time, the two directions are directions tilted by 90° from eachother) are found out. Next, a comparison is made between the curves ofthe two directions, and thereby it can be determined whether themagnetization behavior is of the domain wall displacement type or therotation magnetization type.

The magnitude of uniaxial magnetic anisotropy in the flat surface ispreferably between 0.1 Oe and 10 kOe inclusive, more preferably between1 Oe and 1 kOe inclusive, and even more preferably between 1 Oe and 100Oe inclusive. In regard to whether a material has magnetic anisotropy,and to what extent the material has magnetic anisotropy, an evaluationcan be conveniently performed by varying the direction and makingmeasurement using, for example, a vibrating sample magnetometer (VSM) orthe like. A conventional pressed powder that uses flaky particles isfundamentally different from the present embodiment in that theconventional pressed powder is magnetically isotropic within the flatsurface. As a result of having magnetic anisotropy within the flatsurface, the magnetic characteristics are significantly enhanced.

As described above, it is preferable that the flaky magnetic metalparticles have magnetic anisotropy in one direction within the flatsurface; however, more preferably, when the flaky magnetic metalparticles have either or both of a plurality of concavities and aplurality of convexities that are arranged in a first direction, each ofthe concavities and the convexities having a width of 0.1 μm or more, alength of 1 μm or more, and an aspect ratio of 2 or higher, magneticanisotropy is more easily induced in the first direction, which is morepreferable. From this point of view, more preferably, a width of 1 μm ormore and a length of 10 μm or more are preferred. The aspect ratio ispreferably 5 or higher, and more preferably 10 or higher. By having suchconcavities or convexities provided on the flaky magnetic metalparticles, the adhesiveness between the flaky magnetic metal particlesis enhanced at the time of synthesizing a pressed powder material bypowder-compacting the flaky magnetic metal particles (the concavities orconvexities bring about an anchoring effect of attaching the particlesto neighboring particles). As a result, mechanical characteristics suchas strength and hardness, and thermal stability are enhanced, andtherefore, it is preferable.

In regard to the flaky magnetic metal particles, it is preferable thatthe first directions of either or both of a plurality of concavities anda plurality of convexities are arranged in the direction of the easymagnetization axis. That is, in a case in which there is a large numberof directions of arrangement (=first directions) within the flat surfaceof a flaky magnetic metal particle, it is preferable that the directionof arrangement (=first directions) that accounts for the largestproportion in the large number of directions of arrangement (=firstdirections), coincides with the direction of the easy axis of the flakymagnetic metal particles. Since the length direction in which theconcavities or convexities are arranged, namely, the first direction, islikely to become the easy magnetization axis as a result of the effectof shape magnetic anisotropy, when the flaky magnetic metal particlesare aligned with respect to this direction as the easy magnetizationaxis, magnetic anisotropy may be easily imparted, which is preferable.For the reference, FIG. 3 and FIG. 4 present schematic diagramsillustrating the desired directions of the easy magnetization axis ofthe flaky magnetic metal particles.

In regard to either or both of the concavities and the convexities, itis desirable that five or more on the average of those are included inone flaky magnetic metal particle. Here, five or more concavities may beincluded, five or more convexities may be included, or the sum of thenumber of concavities and the number of convexities may be 5 or larger.More preferably, it is desirable that ten or more of concavities orconvexities are included. It is also desirable that the average distancein the width direction between the respective concavities or convexitiesis between 0.1 μm and 100 μm inclusive. It is also desirable that aplurality of extraneous metal particles containing at least one firstelement selected from the group consisting of Fe, Co and Ni as describedabove and having an average size of between 1 nm and 1 μm inclusive, arearranged along the concavities or convexities. Regarding the method ofdetermining the average size of the extraneous metal particles, theaverage size is calculated by averaging the sizes of a plurality ofextraneous metal particles arranged along the concavities orconvexities, based on SEM observation or TEM observation. When theseconditions are satisfied, magnetic anisotropy is induced in onedirection, which is preferable. Furthermore, the adhesiveness betweenthe flaky magnetic metal particles is enhanced when a pressed powdermaterial is synthesized by powder-compacting the flaky magnetic metalparticles (the concavities or convexities bring about an anchoringeffect of attaching the particles to neighboring particles), and as aresult, mechanical characteristics such as strength and hardness, andthermal stability are enhanced, which is preferable. For reference, FIG.5 presents a schematic diagram of flaky magnetic metal particlesincluding extraneous metal particles. In FIG. 5, extraneous metalparticles 8 are shown. Furthermore, FIG. 6 and FIG. 7 show examples ofscanning electron microscopic photographs of the flaky magnetic metalparticles of the first embodiment.

The flaky magnetic metal particles contain at least one first elementselected from the group consisting of Fe (iron), Co (cobalt), and Ni(nickel).

The flaky magnetic metal particles and the extraneous metal particlesrespectively contain Fe and Co, and the amount of Co is preferablybetween 10 at % and 60 at % inclusive, and more preferably between 10 at% and 40 at % inclusive, with respect to the total amount of Fe and Co.As a result, an appropriately high magnetic anisotropy is likely to beimparted, and the magnetic characteristics described above are enhanced,which is preferable. Furthermore, a Fe—Co-based material is preferablebecause high saturation magnetization can be easily realized.Furthermore, as the composition ranges of Fe and Co are within theranges described above, superior saturation magnetization can berealized, which is preferable. Furthermore, when the compositions of theflaky magnetic metal particles and the extraneous metal particles areequal, thermal stability and mechanical characteristics such as strengthand hardness are easily enhanced, which is preferable.

It is preferable that the flaky magnetic metal particles and theextraneous metal particles contain at least one non-magnetic metalselected from the group consisting of magnesium (Mg), aluminum (Al),silicon (Si), calcium (Ca), zirconium (Zr), titanium (Ti), hafnium (Hf),zinc (Zn), manganese (Mn), barium (Ba), strontium (Sr), chromium (Cr),molybdenum (Mo), silver (Ag), gallium (Ga), scandium (Sc), vanadium (V),yttrium (Y), niobium (Nb), lead (Pb), copper (Cu), indium (In), tin(Sn), and rare earth metal elements. As a result, the thermal stabilityand oxidation resistance of the flaky magnetic metal particles can beincreased. Above all, Al and Si are particularly preferred because theseelements can easily form solid solutions with Fe, Co and Ni, which aremain components of the flaky magnetic metal particles, and contribute toan enhancement of thermal stability and oxidation resistance.

In order to induce magnetic anisotropy, a method of amorphizing thecrystallinity of the flaky magnetic metal particles as far as possible,and thereby inducing magnetic anisotropy in one direction in plane bymeans of a magnetic field or strain, may be employed. In this case, itis desirable that the flaky magnetic metal particles adopt a compositionthat can be easily amorphized as far as possible. From this point ofview, it is preferable that the magnetic metals included in the flakymagnetic metal particles include at least one additive element selectedfrom boron (B), silicon (Si), aluminum (Al), carbon (C), titanium (Ti),zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), molybdenum(Mo), chromium (Cr), copper (Cu), tungsten (W), phosphorus (P), nitrogen(N), gallium (Ga), and yttrium (Y). An additive element having a largerdifference between the atomic radius of the additive element and theatomic radius of at least one first element selected from the groupconsisting of Fe, Co and Ni, is preferred. Furthermore, an additiveelement such that the enthalpy of mixing of at least one first elementselected from the group consisting of Fe, Co and Ni with the additiveelement increases negatively, is preferred. Also, a multicomponentsystem that includes the first element and an additive element and iscomposed of three or more kinds of elements in total, is preferred.Since semimetallic additive elements such as B and Si have slow rates ofcrystallization and are easily amorphized, it is advantageous if thesemimetallic additive elements are mixed into the system. From theviewpoint as described above, B, Si, P, Ti, Zr, Hf, Nb, Y, Cu, and thelike are preferable, and above all, it is more preferable that theadditive element includes any one of B, Si, Zr, and Y. It is alsopreferable that the additive elements are included in a total amount ofbetween 0.001 at % and 80 at % inclusive with respect to the totalamount of the first element and the additive element. The total amountof the additive element is more preferably between 5 at % and 80 at %inclusive, and even more preferably between 10 at % and 40 at %inclusive. As the total amount of the additive element is larger,amorphization proceeds further, and it becomes easier to impart magneticanisotropy, which is preferable (that is, preferable from the viewpointsof low losses and high magnetic permeability). However, on the otherhand, since the proportion of the magnetic metal phase becomes smaller,it is not preferable from the viewpoint that saturation magnetization islowered. However, depending on the use application (for example,magnetic wedges of a motor), even a material having relatively lowsaturation magnetization can be sufficiently used, and there areoccasions in which it is rather preferable that the material specializesin low losses and high magnetic permeability. Meanwhile, magnetic wedgesof a motor are lid-like objects for the slot part into which a coil isinserted. Usually, non-magnetic wedges are used; however, when magneticwedges are employed, the sparseness or denseness of the magnetic fluxdensity is moderated, the harmonic loss is reduced, and the motorefficiency is increased. At this time, it is preferable that saturationmagnetization of the magnetic wedges is higher; however, even withrelatively low saturation magnetization (for example, about 0.5 to 1 T),sufficient effects are manifested. Therefore, it is important to selectan appropriate composition and appropriate amounts of additive elementsdepending on the use application.

It is preferable that the flaky magnetic metal particles have a portioncontaining Fe and Co and having a body-centered cubic (bcc) crystalstructure. As a result, an appropriately high magnetic anisotropy may beeasily imparted, and the magnetic characteristics described above areenhanced, which is preferable. Furthermore, even with a “crystalstructure of a mixed phase of bcc and face-centered cubic (fcc)” thatpartially contains a fcc crystal structure, an appropriately highmagnetic anisotropy may be easily imparted, and the above-mentionedmagnetic characteristics are enhanced. Therefore, it is preferable.

It is preferable that the flat surface is crystallographically oriented.Regarding the direction of orientation, the (110) plane orientation andthe (111) plane orientation are preferred, and the (110) planeorientation is more preferred. In a case in which the crystal structureof the flaky magnetic metal particles is a body-centered cubic (bcc)structure, the (110) plane orientation is preferred, and in a case inwhich the crystal structure of the flaky magnetic metal particles is aface-centered cubic (fcc) structure, the (111) plane orientation ispreferred. As a result, an appropriately high magnetic anisotropy may beeasily imparted, and the above-described magnetic characteristics areenhanced.

Therefore, it is preferable.

Furthermore, regarding a more preferred direction of orientation, the(110) [111] direction and the (111) [110] direction are preferred, andthe (110) [111] direction is more preferred. When the crystal structureof the flaky magnetic metal particles is a body-centered cubic (bcc)structure, orientation in the (110) [111] direction is preferred, andwhen the crystal structure of the flaky magnetic metal particles is aface-centered cubic (fcc) structure, orientation in the (111) [110]direction is preferred. As a result, an appropriately high magneticanisotropy may be easily imparted, and the above-described magneticcharacteristics are enhanced, which is preferable. According to thepresent specification, the “(110) [111] direction” refers to a directionin which the slip plane is the (110) plane or a planecrystallographically equivalent thereto, namely, the {110} plane, andthe slip direction is the [111] direction or a directioncrystallographically equivalent thereto, namely, the <111> direction.The same also applies to the (111) [110] direction. That is, the (111)[110] direction refers to a direction in which the slip plane is the(111) plane or a plane crystallographically equivalent thereto, namely,the {111} plane, and the slip direction is the [110] direction or adirection crystallographically equivalent thereto, namely, the <110>direction.

The lattice strain of the flaky magnetic metal particles 10 ispreferably between 0.01% and 10% inclusive, more preferably between0.01% and 5% inclusive, even more preferably between 0.01% and 1%inclusive, and still more preferably between 0.01% and 0.5% inclusive.As a result, an appropriately high magnetic anisotropy may be easilyimparted, and the magnetic characteristics described above are enhanced,which is preferable.

The lattice strain can be calculated by analyzing in detail the linewidth obtainable by an X-ray diffraction (XRD) method. That is, bydrawing a Halder-Wagner plot or a Hall-Williamson plot, the extent ofcontribution made by expansion of the line width can be separated intothe crystal grain size and the lattice strain. The lattice strain can becalculated thereby. A Halder-Wagner plot is preferable from theviewpoint of reliability. In regard to the Halder-Wagner plot, forexample, N. C. Halder, C. N. J. Wagner, Acta Cryst., 20 (1966), 312-313may be referred to. Here, a Halder-Wagner plot is expressed by thefollowing expression:

$\begin{matrix}{{\frac{\beta^{2}}{\tan^{2}\theta} = {{\frac{K\; \lambda}{D}\frac{\beta}{\tan \; \theta \; \sin \; \theta}} + {16\; ɛ^{2}}}}\mspace{20mu} {ɛ = {ɛ_{\max} = {\frac{\sqrt{2\pi}}{2}\sqrt{\overset{\_}{ɛ^{2}}}}}}\left( {{\beta \text{:}\mspace{14mu} {width}\mspace{14mu} {of}\mspace{14mu} {integration}},\mspace{14mu} {K\text{:}\mspace{14mu} {constant}},{\lambda \text{:}\mspace{14mu} {wavelength}},{D\text{:}\mspace{14mu} {crystal}\mspace{14mu} {grain}\mspace{14mu} {size}},{\sqrt{\overset{\_}{ɛ^{2}}}\text{:}\mspace{14mu} {crystal}\mspace{14mu} {strain}\mspace{14mu} \left( {{root}\mspace{14mu} {mean}\mspace{14mu} {square}} \right)}} \right)} & \left\lbrack {{Mathematical}\mspace{14mu} {Formula}\mspace{14mu} 1} \right\rbrack\end{matrix}$

(β: integrated width, K: constant, λ: wavelength, D: crystal grain size,√ε²: lattice strain (root-mean-square))

That is, β²/tan² θ is plotted on the vertical axis, and β/tan θ·sin θ isplotted on the horizontal axis. The crystal grain size D is calculatedfrom the gradient of the approximation straight line of the plot, andthe lattice strain E is calculated from the ordinate intercept. When thelattice strain obtained by the Halder-Wagner plot of the expressiondescribed above (lattice strain (root-mean-square)) is between 0.01% and10% inclusive, more preferably between 0.01% and 5% inclusive, even morepreferably between 0.01% and 1% inclusive, and still more preferablybetween 0.01% and 0.5% inclusive, an appropriately high magneticanisotropy may be easily imparted, and the magnetic characteristicsdescribed above are enhanced, which is preferable.

The lattice strain analysis described above is a technique that iseffective in a case in which a plurality of peaks can be detected byXRD; however, in a case in which the peak intensities in XRD are weak,and there are few peaks that can be detected (for example, in a case inwhich only one peak is detected), it is difficult to perform ananalysis. In such a case, it is preferable to calculate the latticestrain by the following procedure. First, the composition is determinedby high-frequency inductively coupled plasma (ICP) emissionspectroscopy, energy dispersive X-ray spectroscopy (EDX), or the like,and the composition ratio of three magnetic metal elements, namely, Fe,Co and Ni, is calculated (in a case in which there are only two magneticmetal elements, the composition ratio of two elements; in a case inwhich there is only one magnetic metal element, the composition ratio ofone element (=100%)). Next, an ideal lattice spacing d₀ is calculatedfrom the composition of Fe—Co—Ni (refer to the values published in theliterature, or the like. In some cases, an alloy of the composition isproduced, and the lattice spacing is calculated by making ameasurement). Subsequently, the amount of strain can be determined bydetermining the difference between the lattice spacing d of the peaks ofan analyzed sample and the ideal lattice spacing d₀. That is, in thiscase, the amount of strain is calculated by the expression:(d−d₀)/d₀×100(%). Thus, in regard to the analysis of the lattice strain,it is preferable to use the two above-described techniques appropriatelydepending on the state of peak intensity, and depending on cases, it ispreferable to evaluate the amount of strain by using the two techniquesin combination.

The lattice spacing in the flat surface varies depending on thedirection, and the proportion of the difference between the maximumlattice spacing d_(max) and the minimum lattice spacing d_(min)(=(d_(max)−d_(min))/d_(min)×100(%)) is preferably between 0.01% and 10%inclusive, more preferably between 0.01% and 5% inclusive, even morepreferably between 0.01% and 1% inclusive, and still more preferablybetween 0.01% and 0.5% inclusive. As a result, an appropriately highmagnetic anisotropy may be easily imparted, and the magneticcharacteristics described above are enhanced, which is preferable.Furthermore, the lattice spacing can be conveniently determined by anXRD analysis. When this XRD analysis is carried out while the directionis varied within a plane, the differences in the lattice constantdepending on the direction can be determined.

In regard to crystallites of the flaky magnetic metal particles, it ispreferable that either the crystallites are unidirectionally linked in arow within the flat surface, or the crystallites are rod-shaped and areunidirectionally oriented within the flat surface. As a result, anappropriately high magnetic anisotropy may be easily imparted, and themagnetic characteristics described above are enhanced, which ispreferable.

It is desirable that the ratio a/b of the maximum length a within theflat surface with respect to the minimum length b is between 1 and 5inclusive on the average. As a result, when the particles arepowder-compacted, there is less chance that the particles arepowder-compacted in a bent state, and the stress applied to theparticles is likely to be reduced. That is, strain is reduced, thisleads to the reduction of coercivity and hysteresis loss, and also,since stress is reduced, thermal stability and mechanicalcharacteristics such as strength and toughness can be easily enhanced.

It is desirable that the contour of the flat surface is slightly round.In an extreme example, it is desirable to employ a round contour such asa circle or an ellipse, rather than employing a square or rectangularcontour. As a result, stress is not easily concentrated around thecontour, the magnetic strain of the flaky magnetic metal particles isreduced, the coercivity decreases, and the hysteresis is reduced, whichis desirable. Since stress concentration is reduced, thermal stabilityor mechanical characteristics such as strength and toughness can also beeasily enhanced, which is desirable.

It is desirable that each of the flaky magnetic metal particles furthercomprises a plurality of small magnetic metal particles, that is, 5 ormore particles on the average, on the flat surface. FIG. 8 is aschematic diagram of flaky magnetic metal particles having smallmagnetic metal particles. Small magnetic metal particles 4 are shown.The small magnetic metal particles contain at least one first elementselected from the group consisting of Fe, Co and Ni, and the averageparticle size is between 10 nm and 1 μm inclusive. More preferably, thesmall magnetic metal particles have a composition that is equal to thatof the flaky magnetic metal particles. As the small magnetic metalparticles are provided on the surface of the flat surface, or the smallmagnetic metal particles are integrated with the flaky magnetic metalparticles, the surface of the flaky magnetic metal particles is broughtto an artificially slightly damaged state. As a result, when the flakymagnetic metal particles are powder-compacted together with aninterposed phase that will be described below, adhesiveness is greatlyenhanced. As a result, thermal stability and mechanical characteristicssuch as strength and toughness can be easily enhanced. In order tomanifest such effects at the maximum level, it is desirable that theaverage particle size of the small magnetic metal particles is adjustedto be between 10 nm and 1 μm inclusive, and 5 or more small magneticmetal particles on the average are integrated with the surface, that is,the flat surface, of the flaky magnetic metal particles. When the smallmagnetic metal particles are unidirectionally arranged within the flatsurface, magnetic anisotropy may be easily imparted within the flatsurface, and high magnetic permeability and low losses can be easilyrealized. Therefore, it is more preferable. The average particle size ofthe small magnetic metal particles is determined by observing theparticles by TEM or SEM.

The variation in the particle size distribution of the flaky magneticmetal particles can be defined by the coefficient of variation (CVvalue). That is, CV value (%)=[Standard deviation of particle sizedistribution (μm)/average particle size (μm)]×100. It can be said thatas the CV value is smaller, a sharp particle size distribution with lessvariation in the particle size distribution is obtained. When the CVvalue defined as described above is between 0.1% and 60% inclusive, lowcoercivity, low hysteresis loss, high magnetic permeability, and highthermal stability can be realized, which is preferable. Furthermore,since the variation is small, it is also easy to realize high yield. Amore preferred range of the CV value is between 0.1% and 40% inclusive.

Next, a method for producing the flaky magnetic metal particles of thepresent embodiment will be described.

According to the method for producing the flaky magnetic metal particlesof the present embodiment, a magnetic metal ribbon containing at leastone first element selected from the group consisting of Fe, Co, and Niis produced, the magnetic metal ribbon is heat-treated at a temperatureof between 50° C. and 800° C. inclusive, and the heat-treated magneticmetal ribbon is pulverized. Thus, flaky magnetic metal particles areproduced.

Hereinafter, the production method will be explained specifically. Inregard to the production method, there are no particular limitations,and the production method will be explained only for illustrativepurposes.

A first step is a step of producing a magnetic metal ribbon containingat least one first element selected from the group consisting of Fe, Co,and Ni. The present step is a step of producing a ribbon or a thin filmby using a film-forming apparatus such as a roll quenching apparatus ora sputtering apparatus. At this time, in regard to the film-formingmethod of producing a film using a film-forming apparatus, it isdesirable to produce a film that is imparted with uniaxial anisotropywithin the film plane, through film formation in a magnetic field,rotational film formation or the like. Furthermore, in the case of usinga film-forming apparatus, the thickness can be made small, the structuremay be easily refined, and rotation magnetization may easily occur.Therefore, in the case of producing a rotation magnetization type film,it is desirable to use a film-forming method. Since a roll quenchingapparatus is adequate for synthesis in large quantities, the apparatusis useful when a bulk material is synthesized. In the case of the rollquenching apparatus, a single roll quenching apparatus is convenient andpreferable. Furthermore, when the process is carried out in a state inwhich the roughness of the roll surface is appropriately controlled,concavities or convexities can be easily transferred and produced in thesurface of the ribbon thus synthesized. Therefore, it is very importantto control the roughness of the roll surface. Regarding the roughness ofthe roll surface, it is preferable to polish the roll surface in onedirection (in the length direction of the ribbon) with a polishing paperof between #80 and #4000 inclusive. More preferably, it is preferablethat the roll surface is polished with a polishing paper of between #80and #2000 inclusive, even more preferably between #80 and #600inclusive, and still more preferably near #180. As a result, flakymagnetic metal particles that include concavities or convexities on aflat surface, each of the concavities or convexities having a width of0.1 μm or more, a length of 1 μm or more, and an aspect ratio of 2 orhigher, and have the concavities or convexities arrangedunidirectionally on the flat surface, can be synthesized easily, whichis preferable.

A second step is a step of heat-treating the magnetic metal ribbon at atemperature between 50° C. and 800° C. inclusive. In the present step,the ribbon may be cut into an appropriate size in order to make it easyto introduce the ribbon into an electric furnace for heat treatment. Forexample, the ribbon may be cut into an appropriate size using a mixingapparatus or the like. As a result of performing the present step,pulverizability is likely to be enhanced in the pulverization step,which is the subsequent third step, and thus it is desirable. Regardingthe atmosphere for the heat treatment, a vacuum atmosphere at a lowoxygen concentration, an inert atmosphere, or a reducing atmosphere isdesirable. More desirably, a reducing atmosphere of H₂ (hydrogen), CO(carbon monoxide), CH₄ (methane) or the like is preferred. The reasonfor this is that even if the magnetic metal ribbon has been oxidized,the oxidized metal can be reduced and restored into simple metal byperforming a heat treatment in a reduced atmosphere. As a result, amagnetic metal ribbon that has been oxidized and have lowered saturationmagnetization can be reduced, and thereby saturation magnetization canbe restored. When crystallization of the magnetic metal ribbon proceedsnoticeably due to the heat treatment, characteristics are deteriorated(coercivity increases, and magnetic permeability decreases). Therefore,it is preferable to select the conditions so as to suppress excessivecrystallization. Furthermore, more preferably, it is more desirable toperform the heat treatment in a magnetic field. It is more preferable ifthe magnetic field to be applied is larger; however, it is preferable toapply a magnetic field of 1 kOe or greater, and it is more preferable toapply a magnetic field of 10 kOe or greater. As a result, magneticanisotropy can be manifested within the plane of the magnetic metalribbon, and excellent magnetic characteristics can be realized, which ispreferable.

A third step is a step of producing flaky magnetic metal particles bypulverizing the heat-treated magnetic metal ribbon.

In the present step, the magnetic metal ribbon or thin film may be cutinto an appropriate size using a mixing apparatus or the like, beforethe main pulverization. In the present step, pulverization is performedusing, for example, a pulverizing apparatus such as a bead mill or aplanetary mill. Regarding the pulverizing apparatus, there is noparticular selection for the type. Examples include a planetary mill, abead mill, a rotating ball mill, a vibrating ball mill, an agitatingball mill (attriter), a jet mill, a centrifuge, and techniques combiningmilling and centrifugation. On the occasion of pulverization, whenpulverization is performed while the material is cooled to a temperatureof 0° C. or lower, pulverization can proceed easily, which ispreferable. Particularly, it is desirable to cool the material at theliquid nitrogen temperature (77 K), the dry ice temperature (194 K) orthe like, and particularly above all, it is more desirable to cool thematerial to the liquid nitrogen temperature. As a result, the magneticmetal ribbon is likely to induce low temperature brittleness, andpulverization is carried out easily. That is, pulverization can becarried out efficiently without subjecting the magnetic metal ribbon toexcessive stress or strain, and therefore, it is preferable. However,pulverization may also be achieved sufficiently without cooling in manycases, and in that case, cooling may not be implemented.

In the third step, the thickness of the flaky magnetic metal particlescan be made small by not only simply performing pulverization but alsocombining pulverization with rolling. In a case in which a predeterminedthickness has been obtained by up to the second step, the treatment forrolling may be omitted. Here, rolling may be performed simultaneouslywith pulverization, or rolling may be performed after pulverization, orpulverization may be performed after rolling. In this case, an apparatuscapable of applying a strong gravitational acceleration is preferred,and the process can be performed using, for example, a planetary mill, abead mill, a rotating ball mill, a vibrating ball mill, an agitatingball mill (attriter), a jet mill, a centrifuge, or a technique combiningmilling and centrifugation. For example, a high-power planetary millapparatus is preferable because a gravitational acceleration of severalten G can be applied conveniently. In the case of a high-power planetarymill apparatus, an inclined type planetary mill apparatus is morepreferred, in which the direction of rotational gravitationalacceleration and the direction of revolutionary gravitationalacceleration are not directions on the same straight line, but aredirections that form an angle. In a conventional planetary millapparatus, the direction of rotational gravitational acceleration andthe direction of revolutionary gravitational acceleration are on thesame straight line; however, in an inclined type planetary millapparatus, since the vessel performs a rotating movement in an inclinedstate, the direction of rotational gravitational acceleration and thedirection of revolutionary gravitational acceleration are not on thesame straight line, but form an angle. As a result, power is efficientlytransferred to the sample, and pulverization and rolling is carried withhigh efficiency, which is preferable. Furthermore, in consideration ofmass productivity, a bead mill apparatus that facilitates treatment inlarge quantities is preferred.

It is desirable to perform a treatment so as to obtain flaky magneticmetal particles 10 having a predetermined thickness and a predeterminedaspect ratio, by performing cutting, pulverization and rolling asdescribed above (rolling is carried out as necessary; if not needed,rolling is not performed), and optionally repeating cutting,pulverization and rolling. At this time, when pulverization and rollingare performed so as to obtain a thickness of between 10 nm and 100 μminclusive, more preferably between 10 nm and 1 μm inclusive, and evenmore preferably between 10 nm and 100 nm inclusive, particles that caneasily undergo rotation magnetization are obtained, which is preferable.

Furthermore, for the flaky magnetic metal particles thus obtained, it isdesirable to remove the lattice strain appropriately through a heattreatment. The heat treatment at this time is preferably performed at atemperature of between 50° C. and 800° C. inclusive, as in the case ofthe second step, and regarding the atmosphere for the heat treatment, avacuum atmosphere at a low oxygen concentration, an inert atmosphere, ora reducing atmosphere is desirable. More desirably, a reducingatmosphere of H₂, CO, CH₄ or the like is preferred. Furthermore, morepreferably, it is more desirable to perform the heat treatment in amagnetic field. Since the reasons for these and the details are similarto the case of the second step, no further explanation will be givenhere.

According to the present embodiment described above, flaky magneticmetal particles having low losses can be provided.

Second Embodiment

The flaky magnetic metal particles of the present embodiment aredifferent from the particles of the first embodiment in that at least aportion of the surface of the flaky magnetic metal particles is coveredwith a coating layer that has a thickness of between 0.1 nm and 1 μminclusive and contains at least one second element selected from thegroup consisting of oxygen (O), carbon (C), nitrogen (N), and fluorine(F). Here, any matters overlapping with the contents of the firstembodiment will not be described repeatedly.

FIGS. 9A and 9B are schematic diagrams of the flaky magnetic metalparticles of the present embodiment. The diagrams show a coating layer9.

It is more preferable that the coating layer contains at least onenon-magnetic metal selected from the group consisting of Mg, Al, Si, Ca,Zr, Ti, Hf, Zn, Mn, Ba, Sr, Cr, Mo, Ag, Ga, Sc, V, Y, Nb, Pb, Cu, In,Sn, and rare earth elements, and also contains at least one secondelement selected from the group consisting of oxygen (O), carbon (C),nitrogen (N) and fluorine (F). The non-magnetic metal is particularlypreferably Al or Si, from the viewpoint of thermal stability. In a casein which the flaky magnetic metal particles contain at least onenon-magnetic metal selected from the group consisting of Mg, Al, Si, Ca,Zr, Ti, Hf, Zn, Mn, Ba, Sr, Cr, Mo, Ag, Ga, Sc, V, Y, Nb, Pb, Cu, In,Sn, and rare earth elements, it is more preferable that the coatinglayer contains at least one non-magnetic metal that is the same as thenon-magnetic metal as one of the constituent components of the flakymagnetic metal particles. Among oxygen (O), carbon (C), nitrogen (N),and fluorine (F), it is preferable that the coating layer containsoxygen (O), and it is preferable that coating layer contains an oxide ora composite oxide. This is from the viewpoints of the ease of formingthe coating layer, oxidation resistance, and thermal stability. As aresult, the adhesiveness between the flaky magnetic metal particles andthe coating layer can be enhanced, and the thermal stability andoxidation resistance of the pressed powder material that will bedescribed below can be enhanced. The coating layer cannot only enhancethe thermal stability and oxidation resistance of the flaky magneticmetal particles, but can also enhance the electrical resistance of theflaky magnetic metal particles. By increasing the electrical resistance,the eddy current loss can be suppressed, and the frequencycharacteristics of the magnetic permeability can be enhanced. Therefore,it is preferable that the coating layer 14 has high electricalresistance, and for example, it is preferable that the coating layer 14has a resistance value of 1 mΩ·cm or greater.

Furthermore, the presence of the coating layer is preferable also fromthe viewpoint of magnetic characteristics. In regard to the flakymagnetic metal particles, since the size of the thickness is smallrelative to the size of the flat surface, the metal particles may beregarded as a pseudo-thin film. At this time, a product obtained byforming the coating layer on the surface of the flaky magnetic metalparticles and integrating the coating layer with the particles, may beconsidered to have a pseudo-laminated thin film structure, and themagnetic domain structure is stabilized in terms of energy. As a result,coercivity can be reduced (hysteresis loss is reduced thereby), which ispreferable. At this time, the magnetic permeability also becomes high,and it is preferable. From such a viewpoint, it is more preferable thatthe coating layer is non-magnetic (magnetic domain structure is easilystabilized).

From the viewpoints of thermal stability, oxidation resistance, andelectrical resistance, it is more preferable if the thickness of thecoating layer is larger. However, if the thickness of the coating layeris too large, the saturation magnetization becomes small, and themagnetic permeability also becomes small, which is not preferable.Furthermore, even from the viewpoint of magnetic characteristics, if thethickness is too large, the “effect by which the magnetic domainstructure is stabilized, and a decrease in coercivity, a decrease inlosses, and an increase in magnetic permeability are brought about” isreduced. In consideration of the above-described matters, a preferredthickness of the coating layer is between 0.1 nm and 1 μm inclusive, andmore preferably between 0.1 nm and 100 m inclusive.

According to the present embodiment, flaky magnetic metal particleshaving low losses can be provided.

Third Embodiment

A pressed powder material of the present embodiment includes a pluralityof flaky magnetic metal particles as described in the first embodimentor the second embodiment, and an interposed phase existing between theflaky magnetic metal particles and containing at least one secondelement. Here, any matters overlapping with the contents of the first orsecond embodiment will not be described repeatedly.

FIG. 10 is a schematic diagram of the pressed powder material of thepresent embodiment. FIG. 10 shows an interposed phase 20, a pressedpowder material 100, and a plane 102 of the pressed powder material.

The interposed phase contains at least one second element selected fromthe group consisting of oxygen (O), carbon (C), nitrogen (N), andfluorine (F). This is because the electrical resistance can be increasedthereby. It is preferable that the electrical resistivity of theinterposed phase is higher than the electrical resistivity of the flakymagnetic metal particles. This is because the eddy current loss of theflaky magnetic metal particles can be reduced thereby. Since theinterposed phase exists while surrounding the flaky magnetic metalparticles, the oxidation resistance and thermal stability of the flakymagnetic metal particles can be enhanced, and it is preferable. Aboveall, it is more preferable that the interposed phase contains oxygen,from the viewpoints of high oxidation resistance and high thermalstability. Since the interposed phase also has a role of mechanicallyadhering the flaky magnetic metal particles, it is also preferable fromthe viewpoint of high strength.

In regard to the pressed powder material, it is preferable that the“proportion of arrangement” at which an approximate first direction isarranged in a second direction is 30% or higher. The “proportion ofarrangement” is more desirably 50% or higher, and even more desirably75% or higher. As a result, the magnetic anisotropy becomesappropriately high, and the magnetic characteristics are enhanced asdescribed above, which is preferable. FIG. 11 and FIG. 12 are schematicdiagrams illustrating a method of determining the approximate firstdirection according to the present embodiment, and an example of thedirection of arrangement of the approximate first direction (example ofthe proportion of arrangement). FIG. 11 shows a method of determiningthe approximate first direction. First, for all of the flaky magneticmetal particles to be evaluated in advance, the direction that coincideswith the direction of arrangement of the concavities or convexitiescarried by various flaky magnetic metal particles, which accounts forthe largest proportion, is defined as a first direction. The directionin which the largest number of the first directions of various flakymagnetic metal particles will be arranged in the pressed powder materialas a whole is defined as a second direction. In FIG. 11, the case inwhich the direction of the bold black arrow line serves as the seconddirection, is shown as an example. Next, directions obtained bypartitioning the angle of 360° into angles at an interval of 45° withrespect to the second direction are determined. Next, the firstdirections of the various flaky magnetic metal particles are classifiedaccording to the direction of angle in which the first directions arearranged most closely, and that direction is defined as the “approximatefirst direction”. That is, the first directions are classified into fourclasses such as the direction of 0°, the direction of 45°, the directionof 90°, and the direction of 135°. FIG. 11 illustrates examples of thesecond direction, the first direction, and the approximate firstdirection. FIG. 12 is a schematic diagram illustrating an example of thedirection of arrangement of the approximate first direction (example ofthe proportion of arrangement). Examples of proportions in which theapproximate first direction is arranged in the same direction as thesecond direction (this is defined as the “proportion of arrangement”) is25%, 50%, 75%, and 100%, are shown. When this “proportion ofarrangement” is evaluated, four successive neighboring flaky magneticmetal particles are selected, and the four particles are evaluated. Thisis carried out repeatedly for at least three or more times (the more thebetter; for example, 5 or more times is desirable, and 10 or more timesis more desirable), and thereby, the average value is employed as theproportion of arrangement. Meanwhile, flaky magnetic metal particles inwhich the directions of the concavities or the convexities cannot bedetermined are excluded from the evaluation, and an evaluation of theflaky magnetic metal particles immediately adjacent thereto isperformed. For example, in many of flaky magnetic metal particlesobtained by pulverizing a ribbon synthesized with a single rollquenching apparatus, concavities or convexities attach only on one ofthe flat surfaces, and the other flat surface does not have anyconcavities or convexities attached thereto. When such flaky magneticmetal particles are observed by SEM, the situation in which the flatsurface without any concavities or convexities attached thereto is shownon the image of observation may also occur at a probability of about 50%(even in this case, there may be concavities or convexities actuallyattached to the flat surface on the rear side; however, these flakymagnetic metal particles are excluded from the evaluation).

FIG. 13 shows an example of a scanning electron microscopic photographof the direction of arrangement in the approximate first direction.First, in order to determine a second direction, the direction thatcoincides with the direction of arrangement (first direction) ofconcavities or convexities which accounts for the largest proportion isdecided, and that direction is set as the second direction. In FIG. 13,it is understood from the results of observation of the scanningelectron microscopic photograph, that the direction represented by abold black arrow line in the schematic diagram on the left-hand sidebecomes the second direction. Next, directions each inclined by 45° fromthat direction are determined (four directions, namely, the direction of0°, the direction of 45°, the direction of 90°, and the direction 135°).Next, the first directions in the various flaky magnetic metal particles(for each flaky magnetic metal particle, the first direction is thedirection of the concavities or convexities which accounts for thelargest proportion) are classified based on the direction that isclosest to the direction of a set angle, and the first direction isdetermined as an “approximate first direction”. For example, in FIG. 13,the approximate first direction of the flaky magnetic metal particles of(1) to (6), (12) and (13) is the direction of 0°, the approximate firstdirection of the flaky magnetic metal particles of (7) to (11) is thedirection of 90°, and the approximate first direction of the flakymagnetic metal particle of (14) is the direction of 135°. In FIG. 13,the directions of the approximate first direction of (1) to (14) arerecorded on the scanning electron microscopic photograph as whitearrows. Next, four consecutive neighboring flaky magnetic metalparticles are selected, and the four particles are evaluated. Forexample, since the four particles of (1) to (4) are all in the directionof 0°, which is the same as the second direction, the proportion atwhich the particles are arranged in the same direction is 100%. For thenext four of (5) to (8), since the two particles of (5) and (6) are inthe direction of 0°, which is the same as the second direction, theproportion in which the particles are arranged in the same direction is50%. For the next four of (9) to (12), since only the particle of (12)is in the direction of 0°, which is the same as the second direction,the proportion at which the particles are arranged in the same directionis 25% (although the three particles of (9) to (11) are arranged in thesame direction, since this direction is a direction different from thesecond direction, this direction is not counted as the same direction).Therefore, the proportions in which the particles are arranged in thesame direction (=proportion of arrangement) in connection with the threesets of (1) to (4), (5) to (8), and (9) to (12), are 100%, 50%, and 25%,and the average value is about 58%.

Furthermore, it is preferable that that the largest number of theapproximate first directions are arranged in the direction of the easymagnetization axis of the pressed powder material. That is, it ispreferable that the easy magnetization axis of the pressed powdermaterial is parallel to the second direction. FIG. 14 shows a schematicdiagram illustrating the desired directions of the approximate firstdirection and the easy magnetization axis. Since the length direction inwhich the concavities or convexities are arranged is likely to becomethe easy magnetization axis due to the effect of shape magneticanisotropy, it is preferable to align the directions by taking thisdirection as the easy magnetization axis, since magnetic anisotropy iseasily imparted.

FIG. 15 shows a schematic diagram illustrating the disposition of theinterposed phase. It is preferable that a portion of the interposedphase is attached along the first direction. In other words, it ispreferable that a portion of the interposed phase is attached along thedirection of the concavities or convexities on the flat surfaces of theflaky magnetic metal particles. As a result, magnetic anisotropy can beeasily induced unidirectionally, which is preferable. Such attachment ofthe interposed phase is preferable because the adhesiveness between theflaky magnetic metal particles is enhanced, and consequently, mechanicalcharacteristics such as strength and hardness and thermal stability areenhanced. It is also preferable that the interposed phase includes aparticulate phase. As a result, the adhesiveness between the flakymagnetic metal particles is maintained in an adequate state asappropriate, strain is reduced (since there is a particulate interposedphase between the flaky magnetic metal particles, the stress applied tothe flaky magnetic metal particles is relieved), and coercivity can beeasily reduced (hysteresis loss is reduced, and magnetic permeability isincreased), which is preferable. FIG. 16 shows an example of thescanning electron microscopic photograph of flaky magnetic metalparticles including an interposed phase. It is understood that aninterposed phase is attached along the direction of the concavities orconvexities on the flat surfaces of the flaky magnetic metal particles.

It is preferable that the interposed phase is included in an amount ofbetween 0.01 wt % and 80 wt % inclusive, more preferably between 0.1 wt% and 60 wt % inclusive, and even more preferably between 0.1 wt % and40 wt % inclusive, with respect to the total amount of the pressedpowder material. If the proportion of the interposed phase is too large,the proportion of the flaky magnetic metal particles that have the roleof exhibiting magnetic properties becomes small, and as a result,saturation magnetization or magnetic permeability of the pressed powdermaterial is lowered, which is not preferable. In contrast, if theproportion of the interposed phase is too small, joining between theflaky magnetic metal particles and the interposed phase is weakened, andit is not preferable from the viewpoints of thermal stability andmechanical characteristics such as strength and toughness. Theproportion of the interposed phase that is optimal from the viewpointsof magnetic characteristics such as saturation magnetization andmagnetic permeability, thermal stability, and mechanicalcharacteristics, is between 0.01 wt % and 80 wt % inclusive, morepreferably between 0.1 wt % and 60 wt % inclusive, and even morepreferably between 0.1 wt % and 40 wt % inclusive, with respect to thetotal amount of the pressed powder material.

Furthermore, it is preferable that the proportion of lattice mismatchbetween the interposed phase and the flaky magnetic metal particles isbetween 0.1% and 50% inclusive. As a result, an appropriately highmagnetic anisotropy can be easily imparted, and the above-mentionedmagnetic characteristics are enhanced, which is preferable. In order toset the lattice mismatch to the range described above, the latticemismatch can be realized by selecting the combination of the compositionof the interposed phase and the composition of the flaky magnetic metalparticles 10 as appropriate. For example, Ni of the fcc structure has alattice constant of 3.52 Å, and MgO of the NaCl type structure has alattice constant of 4.21 Å. Thus, the lattice mismatch of the two is(4.21−3.52)/3.52×100=20%. That is, the lattice mismatch can be set to20% by employing Ni of the fcc structure as the main composition of theflaky magnetic metal particles and employing MgO for the interposedphase 20. As such, the lattice mismatch can be set to the rangedescribed above by appropriately selecting the combination of the maincomposition of the flaky magnetic metal particles and the maincomposition of the interposed phase.

The interposed phase may satisfy at least one of the following threeconditions: being a eutectic oxide, containing a resin, and containingat least one magnetic metal selected from the group consisting of Fe,Co, and Ni. This will be explained below.

First, the first “case in which the interposed phase is a eutecticoxide” will be explained. In this case, the interposed phase contains aeutectic oxide containing at least two tertiary elements selected fromthe group consisting of B (boron), Si (silicon), Cr (chromium), Mo(molybdenum), Nb (niobium), Li (lithium), Ba (barium), Zn (zinc), La(lanthanum), P (phosphorus), Al (aluminum), Ge (germanium), W(tungsten), Na (sodium), Ti (titanium), As (arsenic), V (vanadium), Ca(calcium), Bi (bismuth), Pb (lead), Te (tellurium), and Sn (tin).Particularly, it is preferable that the interposed phase contains aneutectic system containing at least two elements from among B, Bi, Si,Zn, and Pb. As a result, the adhesiveness between the flaky magneticmetal particles and the interposed phase becomes strong (interactionstrength increases), and thermal stability and mechanicalcharacteristics such as strength and toughness may be easily enhanced.

Furthermore, the eutectic oxide preferably has a softening point ofbetween 200° C. and 600° C. inclusive, and more preferably between 400°C. and 500° C. inclusive. Even more preferably, the eutectic oxide ispreferably a eutectic oxide containing at least two elements from amongB, Bi, Si, Zn and Pb, and having a softening point of between 400° C.and 500° C. inclusive. As a result, the interaction between the flakymagnetic metal particles and the eutectic oxide becomes strong, and thethermal stability and mechanical characteristics such as strength andtoughness may be easily enhanced. When the flaky magnetic metalparticles are integrated with the eutectic oxide, the two components areintegrated while performing a heat treatment at a temperature near thesoftening point of the eutectic oxide, and preferably a temperatureslightly higher than the softening point. Then, the adhesiveness betweenthe flaky magnetic metal particles and the eutectic oxide increases, andmechanical characteristics can be enhanced. Generally, as thetemperature of the heat treatment is higher to a certain extent, theadhesiveness between the flaky magnetic metal particles and the eutecticoxide increases, and the mechanical characteristics are enhanced.However, if the temperature of the heat treatment is too high, thecoefficient of thermal expansion may become large, and consequently, theadhesiveness between the flaky magnetic metal particles and the eutecticoxide may be decreased on the contrary (if the difference between thecoefficient of thermal expansion of the flaky magnetic metal particlesand the coefficient of thermal expansion of the eutectic oxide becomeslarge, the adhesiveness may be further decreased). Furthermore, in acase in which the crystallinity of the flaky magnetic metal particles isnon-crystalline or amorphous, if the temperature of the heat treatmentis high, crystallization proceeds, and coercivity increases. Therefore,it is not preferable. For this reason, in order to achieve a balancebetween the mechanical characteristics and the coercivitycharacteristics, it is preferable to adjust the softening point of theeutectic oxide to be between 200° C. and 600° C. inclusive, and morepreferably between 400° C. and 500° C. inclusive, and to integrate theflaky magnetic metal particles and the eutectic oxide while performing aheat treatment at a temperature near the softening point of the eutecticoxide, and preferably at a temperature slightly higher than thesoftening point. Furthermore, regarding the temperature at which theintegrated material is actually used in a device or a system, it ispreferable to use the integrated material at a temperature lower thanthe softening point.

Furthermore, it is preferable that the eutectic oxide has a glasstransition temperature. Furthermore, it is desirable that the eutecticoxide has a coefficient of thermal expansion of between 0.5×10⁻⁶/° C.and 40×10⁻⁶/° C. inclusive. As a result, the interaction between theflaky magnetic metal particles 10 and the eutectic oxide becomes strong,and the thermal stability or the mechanical characteristics such asstrength and toughness may be easily enhanced.

Furthermore, it is more preferable that the eutectic oxide includes atleast one or more eutectic particles that are in a particulate form(preferably a spherical form) having a particle size of between 10 nmand 10 μm inclusive. These eutectic particles contain a material that isthe same as the eutectic oxide but is not in a particulate form. In apressed powder material, pores may also exist partially, and thus, itcan be easily observed that a portion of the eutectic oxide exists in aparticulate form, and preferably in a spherical form. Even in a case inwhich there are no pores, the interface of the particulate form orspherical form can be easily discriminated. The particle size of theeutectic particles is more preferably between 10 nm and 1 μm inclusive,and even more preferably between 10 nm and 100 nm inclusive. AS aresult, when stress is appropriately relieved during the heat treatmentwhile the adhesiveness between the flaky magnetic metal particles isretained, the strain applied to the flaky magnetic metal particles canbe reduced, and coercivity can be reduced. As a result, the hysteresisloss is also reduced, and the magnetic permeability is increased.Meanwhile, the particle size of the eutectic particles can be measuredby making an observation by TEM or SEM. In the scanning electronmicroscopic photograph of FIG. 16, it is understood that there is aplurality of spherical eutectic particles formed from the interposedphase.

Furthermore, it is preferable that the interposed phase has a softeningpoint that is higher than the softening point of the eutectic oxide,more preferably has a softening point that is higher than 600° C., andthat the interposed phase further contains intermediate intercalatedparticles containing at least one element selected from the groupconsisting of oxygen (O), carbon (C), nitrogen (N), and fluorine (F).When the intermediate intercalated particles exist between the flakymagnetic metal particles, on the occasion in which the pressed powdermaterial is exposed to high temperature, the flaky magnetic metalparticles being thermally fused with one another and undergoingdeterioration of characteristics can be prevented. That is, it isdesirable that the intermediate intercalated particles exist mainly forthe purpose of thermal stability. Furthermore, when the softening pointof the intermediate intercalated particles is higher than the softeningpoint of the eutectic oxide, and more preferably, the softening point is600° C. or higher, thermal stability can be further increased.

It is preferable that the intermediate intercalated particles contain atleast one non-magnetic metal selected from the group consisting of Mg,Al, Si, Ca, Zr, Ti, Hf, Zn, Mn, Ba, Sr, Cr, Mo, Ag, Ga, Sc, V, Y, Nb,Pb, Cu, In, Sn, and rare earth elements, and contain at least oneelement selected from the group consisting of O (oxygen), C (carbon), N(nitrogen) and F (fluorine). More preferably, from the viewpoints ofhigh oxidation resistance and high thermal stability, an oxide orcomposite oxide containing oxygen is more preferred. Particularly,oxides such as aluminum oxide (Al₂O₃), silicon dioxide (SiO₂), titaniumoxide (TiO₂), and zirconium oxide (Zr₂O₃); and composite oxides such asAl—Si—O are preferred from the viewpoint of high oxidation resistanceand high thermal stability.

Regarding the method for producing a pressed powder material containingintermediate intercalated particles, for example, a method of mixing theflaky magnetic metal particles and the intermediate intercalatedparticles (aluminum oxide (Al₂O₃) particles, silicon dioxide (SiO₂)particles, titanium oxide (TiO₂) particles, zirconium oxide (ZrO₂)particles, and the like) using a ball mill or the like to obtain adispersed state, and then integrating the flaky magnetic metal particlesand the intermediate intercalated particles by press molding or thelike, may be used. The method of dispersing the particles is notparticularly limited as long as it is a method capable of appropriatelydispersing particles.

Next, the second “case in which the interposed phase contains a resin”will be explained. In this case, the resin is not particularly limited,and a polyester-based resin, a polyethylene-based resin, apolystyrene-based resin, a polyvinyl chloride-based resin, a polyvinylbutyral resin, a polyvinyl alcohol resin, a polybutadiene-based resin, aTEFLON (registered trademark)-based resin, a polyurethane resin, acellulose-based resin, an ABS resin, a nitrile-butadiene-based rubber, astyrene-butadiene-based rubber, a silicone resin, other syntheticrubbers, natural rubber, an epoxy resin, a phenolic resin, an allylresin, a polybenzimidazole resin, an amide-based resin, apolyimide-based resin, a polyamideimide resin, or copolymers of thoseresins are used. Particularly, in order to realize high thermalstability, it is preferable that the interposed phase includes asilicone resin or a polyimide resin, both of which have high heatresistance. As a result, the interaction between the flaky magneticmetal particles and the interposed phase becomes strong, and thermalstability and mechanical characteristics such as strength and toughnessmay be easily enhanced.

Next, the third “case in which the interposed phase contains at leastone magnetic metal selected from the group consisting of Fe, Co and Niand has magnetic properties” will be explained. In this case, it ispreferable because, as the interposed phase has magnetic properties, theflaky magnetic metal particles can readily interact magnetically withneighboring particles, and the magnetic permeability is increased.Furthermore, since the magnetic domain structure is stabilized, thefrequency characteristics of the magnetic permeability are alsoenhanced, which is preferable. Meanwhile, the term “magnetic properties”as used herein means ferromagnetism, ferrimagnetism, feeble magnetism,antiferromagnetism, or the like. Particularly, in the case offerromagnetism and ferrimagnetism, the magnetic interaction is stronger,and it is preferable. In regard to the fact that the interposed phasehas magnetic properties, an evaluation can be performed using avibrating sample magnetometer (VSM) or the like. In regard to the factthat the interposed phase contains at least one magnetic metal selectedfrom the group consisting of Fe, Co and Ni and has magnetic properties,an investigation can be performed conveniently by using EDX or the like.

Thus, three conditions of the interposed phase have been explained, andit is preferable that at least one of these three conditions issatisfied; however, it is still acceptable that two or more, or all ofthe three conditions are satisfied. The “case in which the interposedphase is a eutectic oxide” (first case) has slightly inferior mechanicalcharacteristics such as strength as compared to the case in which theinterposed phase is a resin (second case); however, the first case issuperior from the viewpoint that strain may be easily relieved, andlowering of coercivity may easily occur, which is preferable (as aresult, low hysteresis loss and high magnetic permeability may be easilyrealized, which is preferable). Furthermore, eutectic oxides have higherheat resistance compared to resins in many cases, and eutectic oxidesalso have excellent thermal stability, which is preferable. In contrast,the “case in which the interposed phase contains a resin” (second case)has a defect that since the adhesiveness between the flaky magneticmetal particles and the resin is high, stress is likely to be applied(strain is likely to enter), and as a result, coercivity tends toincrease. Particularly, since a resin is highly excellent in view ofmechanical characteristics such as strength, a resin is preferable. The“case in which the interposed phase contains at least one magnetic metalselected from the group consisting of Fe, Co and Ni and has magneticproperties” (third case) is preferable because the flaky magnetic metalparticles may easily interact magnetically with neighboring particles,and particularly because the interposed phase becomes excellent in viewof high magnetic permeability and low coercivity (therefore, lowhysteresis loss). An interposed phase that achieves a good balance canbe produced by using the three conditions as appropriate, or bycombining some of the three conditions, based on the above-describedadvantages and disadvantages.

In regard to the pressed powder material, it is preferable that the flatsurfaces of a plurality of the flaky magnetic metal particles describedabove are oriented in a layered form so as to be parallel to each other.As a result, the eddy current loss of the pressed powder material can bereduced, and thus, it is preferable. Furthermore, since the diamagneticfield can be made small, the magnetic permeability of the pressed powdermaterial can be made high, which is preferable. Also, since theferromagnetic resonance frequency can be made high, the ferromagneticresonance loss can be made small, which is preferable. Such a laminatedstructure is preferable because the magnetic domain structure isstabilized, and low magnetic loss can be realized. Here, if the angleformed by a plane parallel to the flat surface of a flaky magnetic metalparticle and a plane of the pressed powder material is closer to 0°, itis defined that the flaky magnetic metal particles are oriented.Specifically, the aforementioned angle is determined for a large numberof flaky magnetic metal particles 10, such as 10 or more particles, andit is desirable that the average value is preferably between 0° and 45°inclusive, more preferably between 0° and 30° inclusive, and even morepreferably between 0° and 10° inclusive.

The pressed powder material may have a laminated type structure composedof a magnetic layer containing the flaky magnetic metal particles, andan intermediate layer containing any of O, C, and N. In regard to themagnetic layer, it is preferable that the flaky magnetic metal particlesare oriented (oriented such that the flat surfaces are parallel to oneanother). Furthermore, it is preferable that the magnetic permeabilityof the intermediate layer is made smaller than the magnetic permeabilityof the magnetic layer. Through these countermeasures, a pseudo thin filmlaminated structure can be realized, and the magnetic permeability inthe layer direction can be made high, which is preferable. In regard tosuch a structure, since the ferromagnetic resonance frequency can bemade high, the ferromagnetic resonance loss can be made small, which ispreferable. Furthermore, such a laminated structure is preferablebecause the magnetic domain structure is stabilized, and low magneticloss can be realized. In order to further enhance these effects, it ismore preferable to make the magnetic permeability of the intermediatelayer to be smaller than the magnetic permeability of the interposedphase (interposed phase within the magnetic layer). As a result, themagnetic permeability in the layer direction can be made higher in apseudo thin film laminated structure, and therefore, it is preferable.Also, since the ferromagnetic resonance frequency can be made evenhigher, the ferromagnetic resonance loss can be made small, which ispreferable.

Thus, according to the present embodiment, flaky magnetic metalparticles having low losses can be provided.

Fourth Embodiment

A plurality of flaky magnetic metal particles of the present embodimentis a plurality of flaky magnetic metal particles, each particle having aflat surface and a magnetic metal phase containing at least one firstelement selected from the group consisting of Fe, Co and Ni, theparticles having an average thickness of between 10 nm and 100 μminclusive and an average aspect ratio of between 5 and 10,000 inclusive,and having a difference in coercivity on the basis of direction withinthe flat surface. Here, any matters overlapping with the contents of thefirst to third embodiments will not be described repeatedly.

For both the thickness and the aspect ratio, average values areemployed. Specifically, an average value of 10 or more values isemployed.

When it is said to “have a difference in coercivity”, it is implied thatwhen a magnetic field is applied in the directions of 360° within theflat surface and coercivity is measured, there are a direction in whichcoercivity has the maximum value and a direction in which coercivity hasthe minimum value. For example, when coercivity is measured while thedirection is changed at an interval of 22.5° for the angle of 360°within the flat surface, there may be a difference in coercivity. FIG.17 illustrates, as an example, the directions obtainable when coercivityis measured while the direction is changed at an interval of 22.5° forthe angle of 360° within the flat surface of a flaky magnetic metalparticle. When a flaky magnetic metal particle has a difference incoercivity within the flat surface, the minimum coercivity value becomessmall compared to an isotropic case in which there is almost nodifference in coercivity, and thus it is preferable. A material havingmagnetic anisotropy within a flat surface has differences in thecoercivity depending on directions within the flat surface, and theminimum coercivity value becomes small compared to a magneticallyisotropic material. As a result, the hysteresis loss is reduced, and themagnetic permeability is enhanced, which is preferable.

Coercivity can be evaluated conveniently by using a vibrating samplemagnetometer (VSM) or the like. In a case in which coercivity is low,even a coercivity of 0.1 Oe or less can be measured using a low magneticfield unit. Measurement is made by changing the direction within theflat surface with respect to the direction of the magnetic field to bemeasured.

In the flat surface, it is more preferable if the proportion of thedifference in coercivity on the basis of direction is larger, and theproportion is preferably 1% or greater. More preferably, the proportionof the difference in coercivity is 10% or greater; even more preferably,the proportion of the difference in coercivity is 50% or greater; andstill more preferably, the proportion of the difference in coercivity is100% or greater. The proportion of the difference in coercivity as usedherein is defined by the formula: (Hc (max)−Hc (min))/Hc (min)×100(%),by using the maximum coercivity Hc (max) and the minimum coercivity Hc(min) within a flat surface.

The crystal grain size of the magnetic metal phase is preferably 10 nmor less, more preferably 5 nm or less, and even more preferably 2 nm orless. The crystal grain size can be conveniently determined by XRDanalysis. That is, the crystal grain size can be determined by XRD,based on Scherrer's Formula from the diffraction angle and thehalf-value width in relation to the maximum peak among the peaksattributed to the magnetic metal phase. Scherrer's formula is expressedby the formula: D=0.9λ/(β cos θ), wherein D represents the crystal grainsize, λ represents the X-ray wavelength for measurement, β representsthe half-value width, and θ represents Bragg's angle of diffraction. Thecrystal grain size can also be determined by observing a large number ofmagnetic metal phases by TEM (transmission electron microscopy), andaveraging the particle sizes. In a case in which the crystal grain sizeis small, it is preferable to determine the crystal grain size by an XRDanalysis, and in a case in which the crystal grain size is large, it ispreferable to determine the crystal grain size by TEM observation.However, it is preferable to select the measurement method depending onthe circumstances, or to comprehensively determine the crystal grainsize by using both of the methods in combination. The crystal grain sizeof the magnetic metal phase that can be determined by XRD analysis orTEM observation is preferably 10 nm or less, more preferably 5 nm orless, and even more preferably 2 nm or less. As a result, for example,magnetic anisotropy may be easily imparted by applying a heat treatmentin a magnetic field, and the difference in coercivity within the flatsurface becomes large, which is preferable. Furthermore, when it is saidthat the crystal grain size is small, it is implied that the material iscloser to the amorphous state. Therefore, electrical resistance becomeshigher compared to a highly crystalline material, and consequently, theeddy current loss may be easily decreased, which is preferable. Also,the material has excellent corrosion resistance and oxidation resistancecompared to a highly crystalline material, and thus it is preferable.

It is preferable that the magnetic metal phase contains at least oneadditive element selected from the group consisting of B, Si, Al, C, Ti,Zr, Hf, Nb, Ta, Mo, Cr, Cu, W, P, N, Ga, and Y. As a result,amorphization proceeds, magnetic anisotropy may be easily imparted, andthe difference in coercivity within the flat surface becomes large,which is preferable. An additive element which has a large differencebetween the atomic radius of the additive element and the atomic radiusof at least one first element selected from the group consisting of Fe,Co, and Ni, is preferable. Furthermore, an additive element such thatthe enthalpy of mixing of at least one first element selected from thegroup consisting of Fe, Co and Ni with the additive element increasesnegatively, is preferred. Also, a multicomponent system that includesthe first element and an additive element and is composed of three ormore kinds of elements in total, is preferred. Since semimetallicadditive elements such as B and SI have slow rates of crystallizationand are easily amorphized, it is advantageous when the semimetallicadditive elements are mixed into the system. From the viewpoint such asdescribed above, B, Si, P, Ti, Zr, Hf, Nb, Y, Cu, and the like arepreferable, and above all, it is more preferable that the additiveelement includes any one of B, Si, Zr, and Y. It is preferable that thetotal amount of the additive element is altogether between 0.001 at %and 80 at % inclusive with respect to the total amount of the firstelement and the additive element. The total amount is more preferablybetween 5 at % and 80 at % inclusive, and even more preferably between10 at % and 40 at % inclusive. As the total amount of the additiveelement is larger, amorphization proceeds, and it becomes easier toimpart magnetic anisotropy, which is preferable (that is, preferablefrom the viewpoints of low losses and high magnetic permeability).However, on the other hand, since the proportion of the magnetic metalphase becomes smaller, it is not preferable from the viewpoint thatsaturation magnetization is reduced. However, depending on the useapplication (for example, magnetic wedges of a motor), the material canbe sufficiently used even in a case in which saturation magnetization isrelatively low, and there are occasions in which it is rather preferablethat the material specializes in low losses and high magneticpermeability. Meanwhile, magnetic wedges of a motor are lid-like objectsfor the slot part into which a coil is inserted. Usually, non-magneticwedges are used; however, when magnetic wedges are employed, thesparseness or denseness of the magnetic flux density is moderated, theharmonic loss is reduced, and the motor efficiency is increased. At thistime, it is preferable that saturation magnetization of the magneticwedges is higher; however, even with relatively low saturationmagnetization (for example, about 0.5 to 1 T), sufficient effects aremanifested. Therefore, it is important to select an appropriatecomposition and appropriate amounts of additive elements depending onthe use application.

In regard to the flaky magnetic metal particles, the first elementincludes Fe and Co, and the amount of Co is preferably between 10 at %and 60 at % inclusive, and more preferably between 10 at % and 40 at %inclusive, with respect to the total amount of Fe and Co. AS a result,an appropriately high magnetic anisotropy may be easily imparted, andthe magnetic characteristics described above are enhanced, which ispreferable. Furthermore, an Fe—Co-based material is preferable becausehigh saturation magnetization may be easily realized. When thecomposition range of Fe and Co is within the range described above,higher saturation magnetization can be realized, and thus it ispreferable.

It is preferable that the flaky magnetic metal particles contain atleast one non-magnetic metal selected from the group consisting of Mg,Al, Si, Ca, Zr, Ti, Hf, Zn, Mn, Ba, Sr, Cr, Mo, Ag, Ga, Sc, V, Y, Nb,Pb, Cu, In, Sn, and rare earth elements. As a result, thermal stabilityand oxidation resistance of the flaky magnetic metal particles can beenhanced. Among them, Al and Si are particularly preferable becausethese elements may easily form solid solutions with Fe, Co and Ni, whichare main components of the flaky magnetic metal particles, andcontribute to the enhancement of thermal stability or oxidationresistance.

It is preferable that the flaky magnetic metal particles have a portioncontaining Fe and Co and having a body-centered cubic (bcc) crystalstructure. As a result, an appropriately high magnetic anisotropy may beeasily imparted, and the magnetic characteristics as described above canbe enhanced, which is preferable. Furthermore, “a crystal structure of amixed phase of bcc and face-centered cubic (fcc)”, which partially has afcc crystal structure, is also preferable because an appropriately highmagnetic anisotropy may be easily imparted, and the magneticcharacteristics described above are enhanced.

It is preferable that the flat surface is crystallographically oriented.The direction of orientation is preferably the (110) plane orientationor the (111) plane orientation, and more preferably the (110) planeorientation. When the crystal structure of the flaky magnetic metalparticles is the body-centered cubic (bcc) structure, the (110) planeorientation is preferred, and when the crystal structure of the flakymagnetic metal particles is the face-centered cubic (fcc) structure, the(111) plane orientation is preferred. As a result, an appropriately highmagnetic anisotropy may be easily imparted, and the magneticcharacteristics described above are enhanced. Therefore, it ispreferable.

As a more preferable direction of orientation, the (110) [111] directionand the (111) [110] direction are preferred, and the (110) [111]direction is more preferred. When the crystal structure of the flakymagnetic metal particles is the body-centered cubic (bcc) structure,orientation in the (110) [111] direction is preferred, and when thecrystal structure of the flaky magnetic metal particles is theface-centered cubic (fcc) structure, orientation in the (111) [110]direction is preferred. As a result, an appropriately high magneticanisotropy may be easily imparted, and the magnetic characteristicsdescribed above are enhanced, which is preferable. According to thepresent specification, the “(110) [111] direction” refers to a directionin which the slip plane is the (110) plane or a planecrystallographically equivalent thereto, namely, the {110} plane, andthe slip direction is the [111] direction or a directioncrystallographically equivalent thereto, namely, the <111> direction.The same also applies to the (111) [110] direction. That is, the (111)[110] direction refers to a direction in which the slip plane is the(111) plane or a plane crystallographically equivalent thereto, namely,the {111} plane, and the slip direction is the [110] direction or adirection crystallographically equivalent thereto, namely, the <110>direction.

The lattice strain of the flaky magnetic metal particles is preferablybetween 0.01% and 10% inclusive, more preferably between 0.01% and 5%inclusive, even more preferably between 0.01% and 1% inclusive, andstill more preferably between 0.01% and 0.5% inclusive. As a result, anappropriately high magnetic anisotropy may be easily imparted, and themagnetic characteristics described above are enhanced, which ispreferable.

The lattice spacing in the flat surface varies depending on thedirection, and the proportion of the difference between the maximumlattice spacing d_(max) and the minimum lattice spacing d_(min)(=(d_(max) d_(min))/d_(min)×100(%)) is preferably between 0.01% and 10%inclusive, more preferably between 0.01% and 5% inclusive, even morepreferably between 0.01% and 1% inclusive, and still more preferablybetween 0.01% and 0.5% inclusive. As a result, an appropriately highmagnetic anisotropy may be easily imparted, and the magneticcharacteristics described above are enhanced, which is preferable.Furthermore, the lattice spacing can be conveniently determined by anXRD analysis. When this XRD analysis is carried out while the directionis varied within a plane, the differences in the lattice constantdepending on the direction can be determined.

In regard to crystallites of the flaky magnetic metal particles, it ispreferable that either the crystallites are unidirectionally linked in arow within the flat surface, or the crystallites are rod-shaped and areunidirectionally oriented within the flat surface. As a result, anappropriately high magnetic anisotropy may be easily imparted, and themagnetic characteristics described above are enhanced, which ispreferable.

It is preferable that a flat surface of a flaky magnetic metal particlehas either or both of a plurality of concavities and a plurality ofconvexities, the concavities and the convexities being arranged in afirst direction and each having a width of 0.1 μm or more, a length of 1μm or more, and an aspect ratio of 2 or higher. As a result, magneticanisotropy may be easily induced in the first direction, and thedifference in coercivity on the basis of direction in the flat surfacebecomes large, which is preferable. From this point of view, morepreferably, it is preferable that each concavity or convexity has awidth of 1 μm or more and a length of 10 μm or more. The aspect ratio ispreferably 5 or higher, and more preferably 10 or higher. By having suchconcavities or convexities provided on the flaky magnetic metalparticles, the adhesiveness between the flaky magnetic metal particlesis enhanced at the time of synthesizing a pressed powder material bypowder-compacting the flaky magnetic metal particles (the concavities orconvexities bring about an anchoring effect of attaching the particlesto neighboring particles). As a result, mechanical characteristics suchas strength and hardness, and thermal stability are enhanced, andtherefore, it is preferable.

In regard to the flaky magnetic metal particles, it is preferable thatthe first directions of either or both of a largest number ofconcavities and a largest number of convexities are arranged in thedirection of the easy magnetization axis. That is, in a case in whichthere is a large number of directions of arrangement (=first directions)within the flat surface of a flaky magnetic metal particle, it ispreferable that the direction of arrangement (=first directions) thataccounts for the largest proportion in the large number of directions ofarrangement (=first directions), coincides with the direction of theeasy axis of the flaky magnetic metal particles. Since the lengthdirection in which the concavities or convexities are arranged, namely,the first direction, is likely to become the easy magnetization axis dueto the effect of shape magnetic anisotropy, when the flaky magneticmetal particles are aligned with respect to this direction as the easymagnetization axis, magnetic anisotropy may be easily imparted, which ispreferable.

In regard to either or both of the concavities and the convexities, itis desirable that five or more on the average of those are included inone flaky magnetic metal particle. Here, five or more concavities may beincluded, five or more convexities may be included, or the sum of thenumber of concavities and the number of convexities may be 5 or larger.More preferably, it is desirable that ten or more of concavities orconvexities are included. It is also desirable that the average distancein the width direction between the respective concavities or convexitiesis between 0.1 μm and 100 μm inclusive. It is also desirable that aplurality of extraneous metal particles containing at least one firstelement selected from the group consisting of Fe, Co and Ni as describedabove and having an average size of between 1 nm and 1 μm inclusive, arearranged along the concavities or convexities. Regarding the method ofdetermining the average size of the extraneous metal particles, theaverage size is calculated by averaging the sizes of a plurality ofextraneous metal particles arranged along the concavities orconvexities, based on SEM observation or TEM observation. When theseconditions are satisfied, magnetic anisotropy is easily induced in onedirection, which is preferable. Furthermore, the adhesiveness betweenthe flaky magnetic metal particles is enhanced when a pressed powdermaterial is synthesized by powder-compacting the flaky magnetic metalparticles (the concavities or convexities bring about an anchoringeffect of attaching the particles to neighboring particles), and as aresult, mechanical characteristics such as strength and hardness, andthermal stability are enhanced, which is preferable.

It is desirable that the ratio a/b of the maximum length a within theflat surface with respect to the minimum length b is between 1 and 5inclusive, on the average. As a result, when the particles arepowder-compacted, there is less chance that the particles arepowder-compacted in a bent state, and the stress applied to theparticles is likely to be reduced. That is, strain is reduced, thisleads to the reduction of coercivity and hysteresis loss, and also,since stress is reduced, thermal stability and mechanicalcharacteristics such as strength and toughness can be easily enhanced.

It is desirable that the contour of the flat surface is slightly round.In an extreme example, it is desirable to employ a round contour such asa circle or an ellipse, rather than employing a square or rectangularcontour. As a result, stress is not easily concentrated around thecontour, the magnetic strain of the flaky magnetic metal particles isreduced, the coercivity decreases, and the hysteresis is reduced, whichis desirable. Since stress concentration is reduced, thermal stabilityor mechanical characteristics such as strength and toughness can also beeasily enhanced, which is desirable.

It is desirable that each of the flaky magnetic metal particles furthercomprises a plurality of small magnetic metal particles, that is, 5 ormore particles on the average, on the flat surface. The small magneticmetal particles contain at least one first element selected from thegroup consisting of Fe, Co and Ni, and the average particle size isbetween 10 nm and 1 μm inclusive. More preferably, the small magneticmetal particles have a composition that is equal to that of the flakymagnetic metal particles. As the small magnetic metal particles areprovided on the surface of the flat surface, or the small magnetic metalparticles are integrated with the flaky magnetic metal particles, thesurface of the flaky magnetic metal particles is brought to anartificially slightly damaged state. As a result, when the flakymagnetic metal particles are powder-compacted together with aninterposed phase that will be described below, adhesiveness is greatlyenhanced. As a result, thermal stability and mechanical characteristicssuch as strength and toughness can be easily enhanced. In order tomanifest such effects at the maximum level, it is desirable that theaverage particle size of the small magnetic metal particles is adjustedto be between 10 nm and 1 μm inclusive, and 5 or more small magneticmetal particles on the average are integrated with the surface, that is,the flat surface, of the flaky magnetic metal particles. When the smallmagnetic metal particles are unidirectionally arranged within the flatsurface, magnetic anisotropy may be easily imparted within the flatsurface, and high magnetic permeability and low losses can be easilyrealized. Therefore, it is more preferable. The average particle size ofthe small magnetic metal particles is determined by observing theparticles by TEM or SEM.

The variation in the particle size distribution of the flaky magneticmetal particles can be defined by the coefficient of variation (CVvalue). That is, CV value (%)=[Standard deviation of particle sizedistribution (μm)/average particle size (μm)]×100. It can be said thatas the CV value is smaller, a sharp particle size distribution with lessvariation in the particle size distribution is obtained. When the CVvalue defined as described above is between 0.1% and 60% inclusive, lowcoercivity, low hysteresis loss, high magnetic permeability, and highthermal stability can be realized, which is preferable. Furthermore,since the variation is small, it is also easy to realize high yield. Amore preferred range of the CV value is between 0.1% and 40% inclusive.

The average thickness of the flaky magnetic metal particles ispreferably between 10 nm and 100 μm inclusive, and more preferablybetween 1 μm and 100 μm inclusive. Furthermore, the average aspect ratiois preferably between 5 and 10,000 inclusive, and more preferablybetween 10 and 1,000 inclusive. If the flaky magnetic metal particleshave a small thickness and a large aspect ratio, it is preferable fromthe viewpoint that the eddy current loss may be easily reduced; however,on the other hand, the coercivity tends to become slightly higher.Therefore, from the viewpoint of reducing coercivity, it is preferablethat the flaky magnetic metal particles have an appropriate thicknessand an appropriate aspect ratio. When the flaky magnetic metal particleshave a thickness and an aspect ratio in the ranges described above, theflaky magnetic metal particles provide a material having a good balancebetween the eddy current loss and the coercivity.

One effective method for providing the difference in coercivity on thebasis of direction within the flat surface of a flaky magnetic metalparticle, is a method of performing a heat treatment in a magneticfield. It is desirable to perform a heat treatment while a magneticfield is applied unidirectionally within the flat surface. Beforeperforming the heat treatment in a magnetic field, it is desirable tofind the direction of the easy axis within the flat surface (find thedirection in which coercivity is lowest), and to perform the heattreatment while applying a magnetic field in that direction. It is morepreferable when the magnetic field to be applied is larger; however, itis preferable to apply a magnetic field of 1 kOe or greater, and it ismore preferable to apply a magnetic field of 10 kOe or greater. As aresult, magnetic anisotropy can be manifested in the flat surfaces ofthe flaky magnetic metal particles, a difference in coercivity on thebasis of direction can be provided, and excellent magneticcharacteristics can be realized. Therefore, it is preferable. The heattreatment is preferably carried out at a temperature of between 50° C.and 800° C. inclusive. Regarding the atmosphere for the heat treatment,a vacuum atmosphere at a low oxygen concentration, an inert atmosphere,or a reducing atmosphere is desirable. More desirably, a reducingatmosphere of H₂ (hydrogen), CO (carbon monoxide), CH₄ (methane), or thelike is preferred. The reason for this is that even if the flakymagnetic metal particles have been oxidized, the oxidized metal can bereduced and restored into simple metal by subjecting the metal particlesto a heat treatment in a reducing atmosphere. As a result, flakymagnetic metal particles that have been oxidized and have loweredsaturation magnetization can be reduced, and thereby saturationmagnetization can be restored. When crystallization of the flakymagnetic metal particles proceeds noticeably due to the heat treatment,characteristics are deteriorated (coercivity increases, and magneticpermeability decreases). Therefore, it is preferable to select theconditions so as to suppress excessive crystallization.

Furthermore, when flaky magnetic metal particles are synthesized, in acase in which the flaky magnetic metal particles are obtained bysynthesizing a ribbon by a roll quenching method or the like andpulverizing this ribbon, either or both of a plurality of concavitiesand a plurality of convexities may be easily arranged in the firstdirection at the time of ribbon synthesis (concavities or convexitiescan be easily attached in the direction of rotation of the roll). As aresult, the flaky magnetic metal particles may easily have a differencein coercivity on the basis of direction within the flat surface, whichis preferable. That is, the direction in which either or both of aplurality of concavities and a plurality of convexities are arranged inthe first direction with the flat surface, is likely to become thedirection of the easy magnetization axis, and the flat surface may beeffectively provided with a difference in coercivity on the basis ofdirection which is preferable.

According to the present embodiment, flaky magnetic metal particleshaving low losses can be provided.

Fifth Embodiment

The flaky magnetic metal particles of the present embodiment aredifferent from the fourth embodiment in that at least a portion of thesurface of the flaky magnetic metal particles is covered with a coatinglayer having a thickness of between 0.1 nm and 1 μm inclusive andcontaining at least one second element selected from the groupconsisting of oxygen (O), carbon (C), nitrogen (N) and fluorine (F).

In regard to the flaky magnetic metal particles, it is desirable thatthe requirements described in the first and fourth embodiments aresatisfied. Here, since there are overlapping contents, no furtherdescription will be repeated. In regard to the coating layer, it isdesirable that the requirements described in the second embodiment aresatisfied. Here, since there are overlapping contents, no furtherdescription will be repeated.

Thus, according to the present embodiment, flaky magnetic metalparticles having excellent characteristics such as high magneticpermeability, low losses, excellent mechanical characteristics, and highthermal stability, can be provided.

Sixth Embodiment

The pressed powder material of the present embodiment is a pressedpowder material comprising a plurality of flaky magnetic metalparticles, each flat magnetic metal particle having a flat surface and amagnetic metal phase containing at least one first element selected fromthe group consisting of Fe, Co and Ni, the flaky magnetic metalparticles having an average thickness of between 10 nm and 100 μminclusive and an average aspect ratio of between 5 and 10,000 inclusive;and an interposed phase existing between the flaky magnetic metalparticles and containing at least one second element selected from thegroup consisting of oxygen (O), carbon (C), nitrogen (N) and fluorine(F), in which the flat surfaces of the flaky magnetic metal particlesare oriented parallel to a plane of the pressed powder material, and thepressed powder material has a difference in coercivity on the basis ofdirection within the plane of the pressed powder material.

As the angle formed by a face parallel to the flat surface of a flakymagnetic metal particle and a plane of a pressed powder material iscloser to 0°, it is defined that the flaky magnetic metal particles areoriented. FIG. 18 illustrates the angle formed by a face parallel to theflat surface of a flaky magnetic metal particle and a plane of a pressedpowder material. It is desirable that the aforementioned angle isdetermined for a large number of flaky magnetic metal particles, such asten or more particles, and the average value of the angles is preferablybetween 0° and 45° inclusive, more preferably between 0° and 30°inclusive, and even more preferably between 0° and 10° inclusive. Thatis, in regard to the pressed powder material, it is preferable that theflat surfaces of the flaky magnetic metal particles are oriented in alayered form such that the flat surfaces are parallel to one another. Asa result, the eddy current loss of the pressed powder material can bereduced, which is preferable. Furthermore, since the diamagnetic fieldcan be made small, the magnetic permeability of the pressed powdermaterial can be made higher, which is preferable. Also, since theferromagnetic resonance frequency can be made higher, the ferromagneticresonance loss can be reduced, which is preferable. In addition, such alaminated structure is preferable because the magnetic domain structureis stabilized, and low magnetic losses can be realized.

In a case in which coercivity is measured by varying the directionwithin the above-mentioned plane of a pressed powder material (withinthe plane parallel to the flat surface of a flaky magnetic metalparticle), coercivity is measured by, for example, varying the directionat an interval of 22.5° for the angle of 360° within the plane. FIG. 19illustrates, as an example, the directions obtained in a plane of thepressed powder material when coercivity is measured by varying thedirection at an interval of 22.5° for the angle of 360° within theplane.

By having a difference in coercivity within the above-mentioned plane ofa pressed powder material, the minimum coercivity value becomes smallcompared to an isotropic case where there is almost no difference incoercivity, and thus it is preferable. A material having magneticanisotropy within the plane has differences in coercivity depending onthe direction within the plane, and the minimum coercivity value becomessmall compared to a magnetically isotropic material. As a result, thehysteresis loss is reduced, and the magnetic permeability is increased,which is preferable.

In the plane of a pressed powder material (in the plane parallel to theflat surface of a flaky magnetic metal particle), it is more preferableif the proportion of the difference in coercivity on the basis ofdirection is larger, and the proportion is preferably 1% or greater.More preferably, the proportion of the difference in coercivity is 10%or greater; even more preferably, the proportion of the difference incoercivity is 50% or greater; and still more preferably, the proportionof the coercivity difference is 100% or greater. The proportion of thedifference in coercivity as used herein is defined by the formula:(Hc(max)−Hc(min))/Hc(min)×100(%), by using the maximum coercivityHc(max) and the minimum coercivity Hc(min) within a flat surface.

Coercivity can be evaluated conveniently by using a vibrating samplemagnetometer (VSM) or the like. In a case in which coercivity is low,even a coercivity of 0.1 Oe or less can be measured using a low magneticfield unit. Measurement is made by varying the direction within theabove-mentioned plane of a pressed powder material (within the planeparallel to the flat surface of a flaky magnetic metal particle) withrespect to the direction of the magnetic field to be measured.

FIG. 20 illustrates examples of a magnetization curve in a direction inwhich coercivity has the minimum value and a magnetization curve in adirection in which coercivity has the maximum value, within a plane ofthe pressed powder material. The magnetization curve is shifted from thezero point; however, this is merely an error in measurement. Whencoercivity is calculated, a value obtained by dividing the differencebetween the magnetic fields at two points that intersect with abscissa(magnetic fields H1 and H2 where magnetization is zero) by 2 can beemployed (that is, can be calculated by the formula:coercivity=|H2−H1|/2). This sample has a composition of Fe—Co—B—Si(Fe:Co:B:Si=52:23:19:6 (at %), Fe:Co=70:30 (at %), the total amount ofthe additive elements B+Si is 25 at % with respect to the total amountof Fe+Co+B+Si), and it is understood from FIG. 20 that the minimumcoercivity is about 0.1 Oe, while the maximum coercivity is about 0.2Oe. That is, the proportion of the difference in coercivity is(0.2−0.1)/0.1×100=100(%).

FIG. 21 illustrates an example of a difference in coercivity on thebasis of direction in the pressed powder material of the presentembodiment, in a case in which the flat surfaces of flaky magnetic metalparticles are oriented parallel to a plane of the pressed powdermaterial, and there is a difference in coercivity on the basis ofdirection within the plane of the pressed powder material. In thedirection of 22.5°, the coercivity is 0.46 Oe (minimum value), and inthe direction of 90°, the coercivity is 0.55 Oe (maximum value).Therefore, the proportion of the difference in coercivity is(0.55-0.46)/0.46×100=19.6%. As such, the proportion of the difference incoercivity is preferably 1% or greater, and more preferably, theproportion of the difference in coercivity is 10% or greater; theproportion of the difference in coercivity is even more preferably 50%or greater; and the proportion of the difference in coercivity is stillmore preferably 100% or greater.

The pressed powder material may have a laminated structure composed of amagnetic layer containing the flaky magnetic metal particles; and anintermediate layer containing any of O, C and N. In the magnetic layer,it is preferable that the flaky magnetic metal particles are oriented(oriented such that the flat surfaces are parallel to one another).Furthermore, it is preferable that the magnetic permeability of theintermediate layer is made smaller than the magnetic permeability of themagnetic layer. Through these countermeasures, a pseudo thin filmlaminated structure can be realized, and the magnetic permeability inthe layer direction can be made high, which is preferable. In regard tosuch a structure, since the ferromagnetic resonance frequency can bemade high, the ferromagnetic resonance loss can be made small, which ispreferable. Furthermore, such a laminated structure is preferablebecause the magnetic domain structure is stabilized, and low magneticloss can be realized. In order to further enhance these effects, it ismore preferable to make the magnetic permeability of the intermediatelayer to be smaller than the magnetic permeability of the interposedphase (interposed phase within the magnetic layer). As a result, themagnetic permeability in the layer direction can be made higher in apseudo thin film laminated structure, and therefore, it is preferable.Also, since the ferromagnetic resonance frequency can be made evenhigher, the ferromagnetic resonance loss can be made small, which ispreferable.

In regard to the flaky magnetic metal particles that are included in thepressed powder material, it is desirable that the requirements describedin the first, second, fourth, and fifth embodiments are satisfied. Here,any overlapping matters will not be described repeatedly. Furthermore,in regard to the pressed powder material, it is desirable that therequirements described in the third embodiment are satisfied. Here, anyoverlapping matters will not be described repeatedly.

According to the present embodiment, a pressed powder material havinglow losses can be provided.

Seventh Embodiment

The system and the device apparatus of the present embodiment have thepressed powder material of the third or fifth embodiment. Therefore, anymatters overlapping with the contents of the first to fifth embodimentswill not be described repeatedly. Examples of the component parts of thepressed powder material included in these system and device apparatusinclude cores for rotating electric machines such as various motors andgenerators (for example, motors and generators), potential transformers,inductors, transformers, choke coils and filters; and magnetic wedgesfor a rotating electric machine. FIG. 22 shows a conceptual diagram of amotor system as an example of the rotating electric machine system. Amotor system is one system including a control system for controllingthe rotational frequency or the electric power (output power) of amotor. Regarding the mode for controlling the rotational frequency of amotor, there are available control methods that are based on control bya bridge servo circuit, proportional current control, voltage comparisoncontrol, frequency synchronization control, and phase locked loop (PLL)control. As an example, a control method based on PLL is illustrated inFIG. 22. A motor system that controls the rotational frequency of amotor based on PLL comprises a motor; a rotary encoder that converts theamount of mechanical displacement of the rotation of the motor intoelectrical signals, and detects the rotational frequency of the motor; aphase comparator that compares the rotational frequency of the motorgiven by a certain command, with the rotational frequency of the motordetected by the rotary encoder, and outputs the difference of thoserotational frequencies; and a controller that controls the motor so asto make the difference of the rotational frequencies small. On the otherhand, examples of the method for controlling the electric power of themotor include control methods that are based on pulse width modulation(PWM) control, pulse amplitude modulation (PAM) control, vector control,pulse control, bipolar drive, pedestal control, and resistance control.Other examples of the control method include control methods based onmicrostep drive control, multiphase drive control, inverter control, andswitching control. As an example, a control method using an inverter isillustrated in FIG. 22. A motor system that controls the electric powerof the motor using an inverter comprises an alternating current powersupply; a rectifier that converts the output of the alternating currentpower supply to a direct current; an inverter circuit that converts thedirect current to an alternating current based on an arbitraryfrequency; and a motor that is controlled by this alternating current.

FIG. 23 shows a conceptual diagram of a motor 200 as an example of therotating electric machine. In the motor, a first stator (magneto stator)and a second rotor (rotator) are disposed. The diagram illustrates aninner rotor type motor in which a rotor is disposed on the inner side ofa stator; however, the motor may also be of an outer rotor type in whichthe rotor is disposed on the outer side of the stator.

FIG. 24 and FIG. 25 show conceptual diagrams of a motor core (core of amotor) 300. The cores of a stator and a rotor correspond to the motorcore. This will be explained below. FIG. 24 is an exemplary conceptualcross-sectional diagram of a first stator. The first stator has a coreand coils. The coils are wound around some of the protrusions of thecore, which are provided on the inner side of the core. In this core,the pressed powder material of the first, second or third embodiment canbe disposed. FIG. 25 is an exemplary conceptual cross-sectional diagramof the first rotor. The first rotor has a core and coils. The coils arewound around some of the protrusions of the core, which are provided onthe outer side of the core. In this core, the pressed powder material ofthe first, second or third embodiment can be disposed.

FIG. 24 and FIG. 25 are only for illustrative purposes to describeexamples of motors, and the applications of the pressed powder materialare not limited to these. The pressed powder material can be applied toall kinds of motors as cores for making it easy to lead the magneticflux.

Furthermore, a conceptual diagram of a potential transformer/transformer400 is described in FIG. 26, and conceptual diagrams of an inductor aredescribed in FIG. 27 and FIG. 28. These diagrams are only forillustrative purposes. Also for the potential transformer/transformerand the inductor, similarly to the motor core, pressed powder materialscan be applied to all kinds of potential transformers/transformers andinductors in order to make it easy to lead the magnetic flux, or toutilize high magnetic permeability.

FIG. 29 shows an exemplary conceptual diagram of a generator 500 as anexample of the rotating electric machine. The generator 500 comprisesany one of, or both of, a second stator (magneto stator) 530 that usesthe pressed powder material of the first, second or third embodiment asa core; and a second rotor (rotator) 540 that uses the pressed powdermaterial of the first, second or third embodiment as a core. In thediagram, the second rotor (rotator) 540 is disposed on the inner side ofthe second stator 530; however, the second rotor may also be disposed onthe outer side of the second stator. The second rotor 540 is connectedto a turbine 510 provided at an end of the generator 500 through a shaft520. The turbine 510 is rotated by, for example, a fluid supplied fromthe outside, which is not shown in the diagram. Meanwhile, instead ofthe turbine that is rotated by a fluid, the shaft can also be rotated bytransferring dynamic rotation of the regenerative energy of anautomobile or the like. Various known configurations can be employed forthe second stator 530 and the second rotor 540.

The shaft is in contact with a commutator (not shown in the diagram)that is disposed on the opposite side of the turbine with respect to thesecond rotor. The electromotive force generated by rotation of thesecond rotor is transmitted, as the electric power of the generator,after undergoing a voltage increase to the system voltage by means of anisolated phase bus that is not shown in the diagram, and a maintransformer that is not shown in the diagram. Meanwhile, in the secondrotor, an electrostatic charge is generated due to an axial currentresulting from the static electricity from the turbine or powergeneration. Therefore, the generator comprises a brush intended fordischarging the electrostatic charge of the second rotor.

The rotating electric machine of the present embodiment can bepreferably used in railway vehicles. For example, the rotating electricmachine can be preferably used in a motor 200 that drives a railwayvehicle, or a generator 500 that generates electricity for driving arailway vehicle.

Furthermore, FIG. 30 describes a preferred example of the relationbetween the direction of the magnetic flux and the direction ofdisposition of a pressed powder material. First, for both of the domainwall displacement type and the rotation magnetization type, it ispreferable that the flat surfaces of the flaky magnetic metal particlesincluded in a pressed powder material are disposed in a direction inwhich the flat surfaces are parallel to one another as far as possibleare aligned in a layered form, with respect to the direction of themagnetic flux. This is because the eddy current loss can be reduced bymaking the cross-sectional area of the flaky magnetic metal particlesthat penetrate through the magnetic flux, as small as possible.Furthermore, in regard to the domain wall displacement type, it ispreferable that the easy magnetization axis (direction of the arrow) inthe flat surface of a flaky magnetic metal particle is disposed parallelto the direction of the magnetic flux. As a result, the system can beused in a direction in which coercivity is further decreased, andtherefore, the hysteresis loss can be reduced, which is preferable.Furthermore, the magnetic permeability is also made high, and it ispreferable. In contrast, in regard to the rotation magnetization type,it is preferable that the easy magnetization axis (direction of thearrow) in the flat surface of a flaky magnetic metal particle isdisposed perpendicularly to the direction of the magnetic flux. As aresult, the system can be used in a direction in which coercivity isfurther decreased, and therefore, the hysteresis loss can be reduced,which is preferable. That is, it is preferable to understand themagnetization characteristics of a pressed powder material, determinewhether the pressed powder material is of the domain wall displacementtype or the rotation magnetization type (method for determination is asdescribed above), and then dispose the pressed powder material as shownin FIG. 30. In a case in which the direction of the magnetic flux iscomplicated, it may be difficult to dispose the pressed powder materialperfectly as shown in FIG. 30; however, it is preferable to dispose thepressed powder material as shown in FIG. 30 as far as possible. It isdesirable that the method for disposition described above is applied toall of the systems and device apparatuses of the present embodiment (forexample, cores for rotating electric machines such as various motors andgenerators (for example, motors and generators), potential transformers,inductors, transformers, choke coils, and filters; and magnetic wedgesfor a rotating electric machine).

In order for a pressed powder material to be applied to these systemsand device apparatuses, the pressed powder material is allowed to besubjected to various kinds of processing. For example, in the case of asintered body, the pressed powder material is subjected to mechanicalprocessing such as polishing or cutting; and in the case of a powder,the pressed powder material is mixed with a resin such as an epoxy resinor polybutadiene. If necessary, the pressed powder material is furthersubjected to a surface treatment. Also, if necessary, a coil treatmentis carried out.

When the system and device apparatus of the present embodiment are used,a motor system, a motor, a potential transformer, a transformer, aninductor and a generator, all having excellent characteristics (highefficiency and low losses), can be realized.

EXAMPLES

Hereinafter, Examples 1 to 11 of the present invention will be describedin more detail, by making comparisons with Comparative Examples 1 to 5.In regard to the flaky magnetic metal particles obtainable by Examplesand Comparative Examples described below, the thickness and aspect ratioof the flaky magnetic metal particles, the width, length, aspect ratioand number of units of concavities or convexities, and the presence orabsence of extraneous metal particles are summarized in Table 1.Meanwhile, each of the above-mentioned items is calculated as an averagevalue of a large number of particles obtained based on TEM observationor SEM observation.

Example 1

First, a ribbon of Fe—Co—Si—B (Fe:Co=70:30 at %) is produced using asingle roll quenching apparatus. The roll surface is rubbed with apolishing paper in the direction of rotation of the roll, and thus thesurface roughness is adjusted. Next, the ribbon thus obtained issubjected to a heat treatment at 300° C. in a H₂ atmosphere. Next, thisribbon is cut into an appropriate size using a mixing apparatus,subsequently the ribbon pieces thus cut are collected, and the ribbonpieces are subjected to pulverization and rolling at about 1,000 rpm inan Ar atmosphere using a bead mill that uses ZrO₂ balls and a ZrO₂vessel. Thus, the ribbon pieces are converted to a flaky powder.Subsequently, the flaky powder is subjected to a heat treatment at 400°C. in a H₂ atmosphere, and thus flaky magnetic metal particles areobtained. The flaky magnetic metal particles are treated so as to obtaina predetermined size and a predetermined structure, by repeating theoperations of pulverization/rolling and heat treatment described above.Meanwhile, the flaky magnetic metal particles include both concavitiesand convexities. Also, the crystal structure of the magnetic phase ofthe flaky magnetic metal particles is a body-centered cubic structure.The flaky magnetic metal particles thus obtained are mixed with aninorganic oxide interposed phase and are subjected to molding in amagnetic field (flaky particles are oriented). The flaky magnetic metalparticles are subjected to a heat treatment, and thereby a pressedpowder material is obtained.

Example 2

A pressed powder material is obtained in almost the same manner as inExample 1, except that the flaky magnetic metal particles have athickness of 1 μm and an aspect ratio of 100, and the state ofconcavities or convexities is accordingly different.

Example 3

A pressed powder material is obtained in almost the same manner as inExample 1, except that the flaky magnetic metal particles have athickness of 10 pin and an aspect ratio of 20, and the state ofconcavities or convexities is accordingly different.

Example 4

A pressed powder material is obtained in almost the same manner as inExample 1, except that the flaky magnetic metal particles have athickness of 100 μm and an aspect ratio of 5, and the state ofconcavities or convexities is accordingly different.

Example 5

A pressed powder material is obtained in almost the same manner as inExample 1, except that the flaky magnetic metal particles have athickness of 10 nm and an aspect ratio of 1,000, and the state ofconcavities or convexities is accordingly different.

Example 6

A pressed powder material is obtained in almost the same manner as inExample 1, except that the flaky magnetic metal particles have athickness of 10 nm and an aspect ratio of 10,000, and the state ofconcavities or convexities is accordingly different.

Example 7

A pressed powder material is obtained in almost the same manner as inExample 3, except that the flaky magnetic metal particles have noextraneous metal particles along the concavities or convexities.

Example 8

A pressed powder material is obtained in almost the same manner as inExample 3, except that the surface of the flaky magnetic metal particlesis coated with a non-magnetic SiO₂ layer having a thickness of about 10nm by a sol-gel method.

Example 9

A pressed powder material is obtained in almost the same manner as inExample 3, except that the proportion of arrangement of the approximatefirst direction is adjusted to 30% or higher by molding the flakymagnetic metal particles while orienting the metal particles in amagnetic field.

Example 10

A pressed powder material is obtained in almost the same manner as inExample 3, except that the flaky magnetic metal particles include onlyconcavities (not including convexities).

Example 11

A pressed powder material is obtained in almost the same manner as inExample 3, except that the flaky magnetic metal particles include onlyconvexities (not including concavities).

Comparative Example 1

Flaky magnetic metal particles having no concavities or convexities aresynthesized by rubbing the roll surface with polishing paper #4000. Apressed powder material is obtained in almost the same manner as inExample 3, except that the flaky magnetic metal particles have noconcavities or convexities.

Comparative Example 2

A pressed powder material is obtained in almost the same manner as inExample 1, except that the flaky magnetic metal particles have athickness of 8 nm and an aspect ratio of 1,000, and the state ofconcavities or convexities is accordingly different.

Comparative Example 3

A pressed powder material is obtained in almost the same manner as inExample 1, except that the flaky magnetic metal particles have athickness of 120 μm and an aspect ratio of 5, and the state ofconcavities or convexities is accordingly different.

Comparative Example 4

A pressed powder material is obtained in almost the same manner as inExample 1, except that the flaky magnetic metal particles have athickness of 100 μm and an aspect ratio of 4, and the state ofconcavities or convexities is accordingly different.

Comparative Example 5

A pressed powder material is obtained in almost the same manner as inExample 1, except that the flaky magnetic metal particles have athickness of 10 nm and an aspect ratio of 12,000, and the state ofconcavities or convexities is accordingly different.

Next, in regard to the materials for evaluation of Examples 1 to 11 andComparative Examples 1 to 5, the saturation magnetization, the real partof magnetic permeability (μ′), the magnetic permeability loss (tan δ),the change over time in the real part of magnetic permeability (μ′)after 100 hours, the core loss, and the strength ratio are evaluated bythe following methods. The evaluation results are presented in Table 2.

(1) Saturation magnetization: The saturation magnetization at roomtemperature is measured using a VSM.

(2) Real part of magnetic permeability, μ′, and magnetic permeabilityloss (tan δ=μ″/μ′×100(%)): The magnetic permeability of a ring-shapedsample is measured using an impedance analyzer. The real part ofmagnetic permeability, μ′, and the imaginary part of magneticpermeability, μ″, at a frequency of 1 kHz are measured. Furthermore, themagnetic permeability loss or coefficient of loss, tan δ, is calculatedby the formula: μ″/μ′×100(%).

(3) Change over time in real part of magnetic permeability, μ′, after100 hours: A sample for evaluation is heated at a temperature of 60° C.in air for 100 hours, and then the real part of magnetic permeability,μ′, is measured again. Thus, the change over time (real part of magneticpermeability, μ′, after standing for 100 hours/real part of magneticpermeability, μ′, before standing) is determined.

(4) Core loss: The core loss under the operating conditions of 1 kHz and1 T is measured using a B—H analyzer. In a case in which the core losscannot be directly measured under the conditions of 1 kHz and 1 T, thedependency on frequency and the dependency on the magnetic flux densityof the core loss are measured, and the core loss at 1 kHz and 1 T isestimated from the data (then, this estimated value is employed).

(5) Strength ratio: The flexural strength of a sample for evaluation ismeasured, and this is expressed by the ratio of the measured flexuralstrength with respect to the flexural strength of the sample ofComparative Example 1 (=flexural strength of sample forevaluation/flexural strength of sample of Comparative Example 1).

TABLE 1 Concavities and convexities Presence or absence of extraneousAspect Aspect Direction of metal Thickness ratio Width Length ratioarrangement Number particles Remarks Example 1 10 nm 200 0.1 μm 0.5 μm 5Unidirectional 5 Present — Example 2 1 μm 100 5 μm 20 μm 4Unidirectional 10 Present — Example 3 10 μm 20 5 μm 50 μm 10Unidirectional 14 Present — Example 4 100 μm 5 10 μm 50 μm 5Unidirectional 20 Present — Example 5 10 nm 1000 1 μm 2 μm 2Unidirectional 5 Present — Example 6 10 nm 10000 6 μm 20 μm 4Unidirectional 10 Present — Example 7 10 μm 20 6 μm 60 μm 10Unidirectional 12 Absent — Example 8 10 μm 20 5 μm 50 μm 10Unidirectional 14 Present With coating layer Example 9 10 μm 20 5 μm 50μm 10 Unidirectional 14 Present Proportion of arrangement in approximatefirst direction is 30% or greater Example 10 10 μm 20 5 μm 50 μm 10Unidirectional 16 Present Concavities only Example 11 10 μm 20 5 μm 50μm 10 Unidirectional 12 Present Convexities only Comparative 10 μm 20 —— — — — — No concavities example 1 or convexities Comparative 8 nm 10000.5 μm 2 μm 4 Unidirectional 6 Present example 2 Comparative 120 μm 5 10μm 50 μm 5 Unidirectional 18 Present example 3 Comparative 100 μm 4 10μm 50 μm 5 Unidirectional 17 Present example 4 Comparative 10 nm 12000 5μm 20 μm 4 Unidirectional 9 Present example 5

TABLE 2 Saturation Proportion of magnetization μ′ tan δ (%) Core losschange over Strength (T) (1 kHz) (1 kHz) (kW/m³) time of μ′ ratioExample 1 1.7 130 ≈0 500 93 1.3 Example 2 1.7 130 ≈0 520 92 1.3 Example3 1.7 140 ≈0 510 92 1.3 Example 4 1.7 130 ≈0 550 92 1.3 Example 5 1.7140 ≈0 480 92 1.3 Example 6 1.7 150 ≈0 480 92 1.3 Example 7 1.7 120 ≈0540 91 1.2 Example 8 1.6 150 ≈0 490 93 1.4 Example 9 1.7 160 ≈0 480 931.4 Example 10 1.7 140 ≈0 520 92 1.3 Example 11 1.7 140 ≈0 530 92 1.3Comparative 1.7 110 ≈0 600 88 — example 1 Comparative 1.7 150 ≈0 560 911.1 example 2 Comparative 1.7 140 ≈0 540 92 1.1 example 3 Comparative1.7 130 ≈0 550 91 1.1 example 4 Comparative 1.7 150 ≈0 560 91 1.1example 5

As is obvious from Table 1, the flaky magnetic metal particles accordingto Examples 1 to 11 have a thickness of between 10 nm and 100 μminclusive and an aspect ratio of between 5 and 10,000 inclusive, andinclude five or more concavities or convexities on the flat surface,each concavity or convexity having a width of 0.1 μm or more, a lengthof 1 μm or more, and an aspect ratio of 2 or higher. Furthermore, theconcavities or convexities are unidirectionally arranged on the flatsurface. In the Examples other than Example 7, a plurality of extraneousmetal particles having an average size of between 1 nm and 1 μminclusive is arranged along the concavities or convexities. Example 8has a coating layer formed on the surface of the flaky magnetic metalparticles of Example 3. In Example 9, the proportion of arrangement inthe approximate first direction is 30% or higher. In Example 10, theflaky magnetic metal particles include concavities only, and in Example11, the flaky magnetic metal particles include convexities only.

As is obvious from Table 2, it is understood that the pressed powdermaterials that use the flaky magnetic metal particles of Examples 1 to11 are excellent particularly in terms of the magnetic permeability, thecore loss, the proportion of change over time in the magneticpermeability, and the strength ratio, compared to the pressed powdermaterial of Comparative Example 1. That is, it is understood that thepressed powder materials have excellent magnetic characteristics,thermal stability, and mechanical characteristics. It is also understoodthat Examples 8 and 9 are slightly superior to Example 3 in terms of themagnetic permeability, the core loss, the proportion of change over timein the magnetic permeability, and the strength ratio. That is, it isunderstood that Examples 8 and 9 have slightly superior magneticcharacteristics, thermal stability, and mechanical characteristics.Furthermore, it is understood that Example 3 is slightly superior toExample 7 in terms of the magnetic permeability, the core loss, theproportion of change over time in the magnetic permeability, and thestrength ratio. That is, it is understood that Example 3 has slightlysuperior magnetic characteristics, thermal stability, and mechanicalcharacteristics. It is understood that Comparative Examples 2 to 5 haveconcavities or convexities formed thereon; however, the thicknesses andthe aspect ratios of the flaky magnetic metal particles are not in thedefined ranges, and in this case, the flaky magnetic metal particles areslightly inferior particularly in terms of the mechanicalcharacteristics such as strength. It is understood that the pressedpowder materials of Examples 1 to 11 also have excellent magneticcharacteristics such as high saturation magnetization, high magneticpermeability, and low losses. Meanwhile, since the materials are pressedpowder materials, the materials can be applied to complex shapes.

EXAMPLES

In the following description, Examples 12 to 28 of the invention will beexplained in more detail by making comparisons with Comparative Examples6 to 10. In regard to the flaky magnetic metal particles obtainable byExamples and Comparative Examples described below, the thickness andaspect ratio of the flaky magnetic metal particles, the proportion (%)of the difference in coercivity in the flat surface of a flaky magneticmetal particle, and the proportion (%) of the difference in coercivityin a plane of a pressed powder material are summarized in Table 3. Thethickness and the aspect ratio are respectively calculated as averagevalues of a large number of particles obtained based on TEM observationor SEM observation.

Example 12

First, a ribbon of Fe—Co—B—Si (Fe:Co:B:Si=52:23:19:6 (at %), Fe:Co=70:30(at %), the total amount of the additive elements B+Si is 25 at % withrespect to the total amount of Fe+Co+B+Si) is produced using a singleroll quenching apparatus. Next, the ribbon thus obtained is subjected toa heat treatment at 300° C. in a H₂ atmosphere. Next, this ribbon ispulverized using a mixing apparatus, and is subjected to a heattreatment in a magnetic field at 400° C. in a H₂ atmosphere. Thus, flakymagnetic metal particles are obtained. The flaky magnetic metalparticles thus obtained have a thickness of 10 μm and an aspect ratio of20, and the crystal grain size of the magnetic metal phase is about 2nm. The flaky magnetic metal particles thus obtained are mixed with aninorganic oxide interposed phase (B₂O₃—Bi₂O₃—ZnO), the mixture issubjected to molding in a magnetic field (orienting the flakyparticles), and the resulting product is subjected to a heat treatmentin a magnetic field. Thus, a pressed powder material is obtained. Duringthe heat treatment in a magnetic field, a magnetic field is applied inthe direction of the easy magnetization axis, and then a heat treatmentis carried out.

Example 13

In Example 12, the ribbon pieces are collected, and the ribbon piecesare subjected to pulverization and rolling at about 1,000 rpm in an Aratmosphere using a bead mill that uses ZrO₂ balls and a ZrO₂ vessel.Thus, the ribbon pieces are converted to a flaky powder. The flakypowder is treated so as to acquire a predetermined size and apredetermined structure, by repeating the operations ofpulverization/rolling and a heat treatment. Except for these, theprocedure is almost the same as that of Example 12. The flaky magneticmetal particles thus obtained have a thickness of 10 nm and an aspectratio of 200, and the crystal grain size of the magnetic metal phase isabout 2 nm.

Example 14

A pressed powder material is produced in almost the same manner as inExample 13, except that the flaky magnetic metal particles have athickness of 1 μm and an aspect ratio of 100.

Example 15

A pressed powder material is produced in almost the same manner as inExample 13, except that the flaky magnetic metal particles have athickness of 100 μm and an aspect ratio of 5.

Example 16

A pressed powder material is produced in almost the same manner as inExample 13, except that the flaky magnetic metal particles have athickness of 10 nm and an aspect ratio of 1,000.

Example 17

A pressed powder material is produced in almost the same manner as inExample 13, except that the flaky magnetic metal particles have athickness of 10 nm and an aspect ratio of 10,000.

Example 18

A pressed powder material is produced in almost the same manner as inExample 12, except that the proportion of the difference in coercivityin the flat surface of a flaky magnetic metal particle is adjusted to12%, and the proportion of the difference in coercivity in a plane ofthe pressed powder material is adjusted to 10%, by controlling theconditions for the heat treatment in a magnetic field.

Example 19

A pressed powder material is produced in almost the same manner as inExample 12, except that the proportion of the difference in coercivityin the flat surface of a flaky magnetic metal particle is adjusted to52%, and the proportion of the difference in coercivity in a plane ofthe pressed powder material is adjusted to 50%, by controlling theconditions for the heat treatment in a magnetic field.

Example 20

At the time of synthesizing a ribbon, the roll surface is rubbed with apolishing paper in the direction of rotation of the roll, and therebythe surface roughness is adjusted. The flat surfaces of the flakymagnetic metal particles thus obtainable have both a plurality ofconcavities and a plurality of convexities arranged in a firstdirection, each concavity or convexity having a width of 0.1 μm or more,a length of 1 μm or more, and an aspect ratio of 2 or higher. Except forthese, the procedure is almost the same as that of Example 12.

Example 21

A pressed powder material is produced in almost the same manner as inExample 12, except that at the time of synthesizing a ribbon, the flakymagnetic metal particles thus obtainable are given with a lattice strainof 0.5% by controlling the quenching conditions.

Example 22

A pressed powder material is produced in almost the same manner as inExample 12, except that at the time of synthesizing a ribbon, the flakymagnetic metal particles thus obtainable are oriented in the (110)direction by controlling the quenching conditions.

Example 23

A pressed powder material is produced in almost the same manner as inExample 12, except that by controlling the quenching conditions and thepulverization conditions at the time of synthesizing a ribbon, five ormore on the average of small magnetic metal particles having an averageparticle size of between 10 nm and 1 μm inclusive are attached on theflat surface of each flaky magnetic metal particle thus obtainable.

Example 24

A pressed powder material is produced in almost the same manner as inExample 12, except that the composition is changed to Fe—Co—B—Zr(Fe:Co:B:Zr=63:27:4:6 (at %), Fe:Co=70:30 (at %), and the total amountof the additive elements B+Zr is 10 at % with respect to the totalamount of Fe+Co+B+Zr).

Example 25

A pressed powder material is produced in almost the same manner as inExample 12, except that the composition is changed to Fe—Co—B—Y(Fe:Co:B:Y=63:27:4:6 (at %), Fe:Co=70:30 (at %), and the total amount ofthe additive elements B+Y is 10 at % with respect to the total amount ofFe+Co+B+Y).

Example 26

A pressed powder material is produced in almost the same manner as inExample 12, except that the composition is changed to Fe—Co—Si(Fe:Co:Si=66.5:28.5:5.0 (at %), Fe:Co=70:30 (at %), and the total amountof the additive element Si is 5.0 at % with respect to the total amountof Fe+Co+Si).

Example 27

A pressed powder material is produced in almost the same manner as inExample 12, except that the surface of the flaky magnetic metalparticles is coated with a non-magnetic SiO₂ layer having a thickness ofabout 10 nm by a sol-gel method.

Example 28

A pressed powder material is produced in almost the same manner as inExample 12, except that a resin interposed phase (polyimide-based resin)is used instead of the inorganic oxide interposed phase(B₂O₃—Bi₂O₃—ZnO).

Comparative Example 6

Commercially available Fe—Si—Cr—Ni flaky particles are used. The flakymagnetic metal particles have a thickness of about 400 nm and an aspectratio of about 100. A pressed powder material is obtained by mixing theflaky magnetic metal particles together with an interposed phase, andperforming molding (molding in a magnetic field and a heat treatment ina magnetic field are not carried out).

Comparative Example 7

A pressed powder material is produced in almost the same manner as inExample 12, except that the flaky magnetic metal particles have athickness of 8 nm and an aspect ratio of 1,000.

Comparative Example 8

A pressed powder material is produced in almost the same manner as inExample 12, except that the flaky magnetic metal particles have athickness of 120 μm and an aspect ratio of 5.

Comparative Example 9

A pressed powder material is produced in almost the same manner as inExample 12, except that the flaky magnetic metal particles have athickness of 100 μm and an aspect ratio of 4.

Comparative Example 10

A pressed powder material is produced in almost the same manner as inExample 12, except that the flaky magnetic metal particles have athickness of 10 nm and an aspect ratio of 12,000.

Next, in regard to the materials for evaluation of Examples 12 to 28 andComparative Examples 6 to 10, the saturation magnetization, the realpart of magnetic permeability (μ′), the magnetic permeability loss (tanδ), the change over time in the real part of magnetic permeability (μ′)after 100 hours, the core loss, and the strength ratio are evaluated bythe following methods. The evaluation results are presented in Table 4.

(1) Saturation magnetization: The saturation magnetization at roomtemperature is measured using a VSM.

(2) Real part of magnetic permeability, μ′, and magnetic permeabilityloss (tan δ=μ″/μ′×100(%)): The magnetic permeability of a ring-shapedsample is measured using an impedance analyzer. The real part ofmagnetic permeability, μ′, and the imaginary part of magneticpermeability, μ″, at a frequency of 100 Hz are measured. Furthermore,the magnetic permeability loss or coefficient of loss, tan δ, iscalculated by the formula: μ″/μ′×100(%).

(3) Change over time in real part of magnetic permeability, μ′, after100 hours: A sample for evaluation is heated at a temperature of 60° C.in air for 100 hours, and then the real part of magnetic permeability,μ′, is measured again. Thus, the change over time (real part of magneticpermeability, μ′, after standing for 100 hours/real part of magneticpermeability, μ′, before standing) is determined.

(4) Core loss: The core loss under the operating conditions of 100 Hzand 1 T is measured using a B—H analyzer. In a case in which the coreloss cannot be directly measured under the conditions of 100 Hz and 1 T,the dependency on frequency and the dependency on the magnetic fluxdensity of the core loss are measured, and the core loss at 100 Hz and 1T is estimated from the data (then, this estimated value is employed).

(5) Strength ratio: The flexural strength of a sample for evaluation ismeasured, and this is expressed by the ratio of the measured flexuralstrength with respect to the flexural strength of the sample ofComparative Example 1 (=flexural strength of sample forevaluation/flexural strength of sample of Comparative Example 6).

TABLE 3 Proportion of difference in Proportion of coercivity in flatdifference in surface of flaky coercivity in plane of Thick- Aspectmagnetic metal particle pressed powder ness ratio (%) material (%)Remarks Example 12 10 μm 20 105  100  — Example 13 10 nm 200 80 70 —Example 14  1 μm 100 90 80 — Example 15 100 μm  5 100  90 — Example 1610 nm 1000 80 70 — Example 17 10 nm 10000 80 70 — Example 18 10 μm 20 1210 — Example 19 10 μm 20 52 50 — Example 20 10 μm 20 110  105  Aplurality of concavities and convexities Example 21 10 μm 20 115  107 Lattice strain Example 22 10 μm 20 110  105  Orientation in (110)direction Example 23 10 μm 20 102  100  Attachment of small magneticmetal particles Example 24 10 μm 20 50 48 Fe—Co—B—Zr Example 25 10 μm 2055 52 Fe—Co—B—Y Example 26 10 μm 20 17 15 Fe—Co—Si Example 27 10 μm 20105  102  With coating layer Example 28 10 μm 20 105  23 Polyimide-basedresin Comparative 400 nm  100  ≈0    ≈0   — example 6 Comparative  8 nm1000 50 40 — example 7 Comparative 120 μm  5 80 70 — example 8Comparative 100 μm  4 70 60 — example 9 Comparative 10 nm 12000 50 40 —example 10

TABLE 4 Saturation Proportion of magnetization μ′ tan δ (%) Core losschange over Strength (T) (1 kHz) (1 kHz) (kW/m³) time of μ′ ratioExample 12 1.0 90 ≈0 15 92 1.2 Example 13 1.0 85 ≈0 18 92 1.2 Example 141.0 88 ≈0 16 93 1.2 Example 15 1.0 78 ≈0 20 93 1.2 Example 16 1.0 82 ≈018 92 1.2 Example 17 1.0 80 ≈0 15 92 1.2 Example 18 1.0 50 ≈0 40 93 1.2Example 19 1.0 60 ≈0 22 93 1.3 Example 20 1.0 93 ≈0 13 94 1.4 Example 211.0 93 ≈0 13 94 1.4 Example 22 1.0 97 ≈0 13 94 1.4 Example 23 1.0 93 ≈013 94 1.4 Example 24 1.3 30 ≈0 60 92 1.3 Example 25 1.3 33 ≈0 50 92 1.3Example 26 1.8 25 ≈0 180 92 1.3 Example 27 1.0 92 ≈0 13 94 1.4 Example28 1.0 70 ≈0 150 92 3.0 Comparative 1.0 20 ≈0 500 88 — example 6Comparative 1.0 87 ≈0 20 90 1.1 example 7 Comparative 1.0 88 ≈0 21 901.1 example 8 Comparative 1.0 86 ≈0 20 90 1.1 example 9 Comparative 1.088 ≈0 21 90 1.1 example 10

As is obvious from Table 3, the flaky magnetic metal particles accordingto Examples 12 to 28 have a thickness of between 10 nm and 100 μminclusive and an aspect ratio of between 5 and 10,000 inclusive. Theflaky magnetic metal particles have differences in coercivity dependingon the direction within the flat surface, and also have differences incoercivity depending on the direction within a plane of the pressedpowder materials. Examples 18 and 19 have lower proportions ofdifference in coercivity compared to Example 12. Example 20 has both aplurality of concavities and a plurality of convexities on the flatsurface, the concavities and the convexities being arranged in a firstdirection and each having a width of 0.1 μm or more, a length of 1 μm ormore, and an aspect ratio of 2 or higher. Example 21 is given with alattice strain of 0.5%. Example 22 has the flaky magnetic metalparticles oriented in the (110) direction. Example 23 has five or moreon the average of small magnetic metal particles having an averageparticle size of between 10 nm and 1 μm inclusive, attached on the flatsurfaces of the flaky magnetic metal particles. Example 24 has aFe—Co—B—Zr composition, Example 25 has a Fe—Co—B—Y composition, andExample 26 has a Fe—Co—Si composition. Example 27 has a coating layerformed on the surface of the flaky magnetic metal particles of Example12. Example 28 has a resin interposed phase as the interposed phase.

As is obvious from Table 4, it is understood that the pressed powdermaterials that use the flaky magnetic metal particles of Examples 12 to28 are excellent in terms of the magnetic permeability, the core loss,the proportion of change over time in the magnetic permeability, and thestrength ratio, compared to the pressed powder material of ComparativeExample 6. That is, it is understood that the pressed powder materialshave excellent magnetic characteristics, thermal stability, andmechanical characteristics. Furthermore, it is understood that Examples20 to 23 and 27 are slightly superior to Example 12 in terms of themagnetic permeability, the core loss, the proportion of change over timein the magnetic permeability, and the strength ratio. That is, it isunderstood that the Examples have slightly superior magneticcharacteristics, thermal stability, and mechanical characteristics.Furthermore, it is understood that Example 28 is inferior to Example 12in terms of the magnetic permeability and the core loss; however,Example 28 is markedly superior in terms of the strength ratio. That is,it is understood that in the case of using a resin-based interposedphase, the pressed powder material is slightly inferior in terms ofmagnetic characteristics compared to the case of using an inorganicoxide interposed phase; however, the pressed powder material is markedlysuperior in terms of mechanical characteristics such as strength. It isunderstood that Examples 18 and 19 are slightly inferior to Example 12particularly in terms of the magnetic permeability and the core loss,due to the lower proportions of difference in coercivity. In Examples 24to 26, the saturation magnetization in particular can be changed bychanging the composition. Depending on the use applications (forexample, magnetic wedges of motors), even a material having relativelylow saturation magnetization can be sufficiently used, and there areoccasions in which such a material specializing in low losses and highmagnetic permeability is rather preferable. Therefore, in that case,materials having a saturation magnetization in the 1 T class, such asExamples 12 to 23, 27, and 28, can be used. Meanwhile, in a case inwhich high saturation magnetization is required as in the case of amotor core, materials having high saturation magnetization, such asExamples 24 to 26, and particularly Example 26, can be used. It isimportant to select the composition and the amount of additive elementsaccording to the use applications. Comparative Examples 7 to 10 havedifferences in coercivity depending on the direction in the flat surfaceof a flaky magnetic metal particle, and also have differences incoercivity depending on the direction in a plane of the pressed powdermaterial. However, the thicknesses and the aspect ratios of the flakymagnetic metal particles are not in the defined ranges. In this case, itis understood that the pressed powder materials are slightly inferiorparticularly in terms of the proportion of change over time in themagnetic permeability and the strength ratio. In summary, it isunderstood that the pressed powder materials of Examples 12 to 28 haveexcellent magnetic characteristics and mechanical characteristics, suchas high saturation magnetization, high magnetic permeability, a low coreloss, a small “proportion of change over time in the magneticpermeability”, and high strength. Meanwhile, since the materials arepressed powder materials, the materials can be applied to complexshapes.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, a plurality of flaky magnetic metalparticles, a pressed powder material, and a rotating electric machinedescribed herein may be embodied in a variety of other forms;furthermore, various omissions, substitutions and changes in the form ofthe devices and methods described herein may be made without departingfrom the spirit of the inventions. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the inventions.

Clause 1. A plurality of flaky magnetic metal particles, each flakymagnetic metal particle comprising:

a flat surface having either or both of a plurality of concavities and aplurality of convexities arranged in a first direction, each concavityor convexity having a width of 0.1 μm or more, a length of 1 μm or more,and an aspect ratio of 2 or higher; and

at least one first element selected from the group consisting of iron(Fe), cobalt (Co), and nickel (Ni),

the flaky magnetic metal particles having an average thickness ofbetween 10 nm and 100 μm inclusive and an average aspect ratio ofbetween 5 and 10,000 inclusive.

Clause 2. The flaky magnetic metal particles according to clause 1,wherein each of the flaky magnetic metal particles has five or more onthe average of either or both of concavities and convexities.Clause 3. The flaky magnetic metal particles according to clause 1 or 2,wherein each of the flaky magnetic metal particles further comprises, onthe flat surface, a plurality of extraneous metal particles containingat least one of the first elements and having an average size of between1 nm and 1 μm inclusive, and some of the extraneous metal particles arearranged along the first direction.Clause 4. The flaky magnetic metal particles according to any of clauses1-3, wherein the flaky magnetic metal particles have magnetic anisotropywithin the flat surface.Clause 5. The flaky magnetic metal particles according to clause 4,wherein the largest number of the first directions are arranged in thedirection of the easy magnetization axis.Clause 6. The flaky magnetic metal particles according to any of clauses1-5, wherein the magnetization behavior of the flaky magnetic metalparticles proceeds by domain wall displacement.Clause 7. The flaky magnetic metal particles according to any of clauses1-5, wherein the magnetization behavior of the flaky magnetic metalparticles proceeds by rotation magnetization.Clause 8. The flaky magnetic metal particles according to any of clauses1-7, wherein the lattice strain of the flaky magnetic metal particles isbetween 0.01% and 10% inclusive.Clause 9. The flaky magnetic metal particles according to any of clauses1-8, wherein the flaky magnetic metal particles have a body-centeredcubic crystal structure.Clause 10. The flaky magnetic metal particles according to any ofclauses 1-9, wherein the flaky magnetic metal particles contain Fe andCo, and the amount of Co is between 10 at % and 60 at % inclusive withrespect to the total amount of Fe and Co.Clause 11. The flaky magnetic metal particles according to any ofclauses 1-10, wherein the flat surface has the (110) plane orientationor the (111) plane orientation.Clause 12. The flaky magnetic metal particles according to any ofclauses 1-11, wherein the ratio of the maximum length with respect tothe minimum length within the flat surface is between 1 and 5 inclusiveon the average, and

each of the flaky magnetic metal particles further comprises a pluralityof small magnetic metal particles on the flat surface, the number of thesmall magnetic metal particles disposed on the flat surface being 5 ormore on the average, and the small magnetic metal particles containingat least one of the first elements and having an average particle sizeof between 10 nm and 1 μm inclusive.

Clause 13. The flaky magnetic metal particles according to any ofclauses 1-12, wherein at least a portion of the surface of the flakymagnetic metal particles is coated with a coating layer having athickness of 0.1 nm and 1 μm inclusive and containing at least onesecond element selected from the group consisting of oxygen (O), carbon(C), nitrogen (N) and fluorine (F).Clause 14. A pressed powder material comprising a plurality of the flakymagnetic metal particles according to any of clauses 1-13; and aninterposed phase provided between the flaky magnetic metal particles andcontaining at least one of the second elements.Clause 15. The pressed powder material according to clause 14, whereinthe proportion of arrangement of an approximate first direction arrangedin a second direction is 30% or higher.Clause 16. The pressed powder material according to clause 14 or 15,wherein the largest number of the approximate first directions arearranged in the direction of the easy magnetization axis of the pressedpowder material.Clause 17. The pressed powder material according to any of clauses14-16, wherein the interposed phase is attached along the firstdirection.Clause 18. A rotating electric machine comprising the pressed powdermaterial according to any of clauses 14-17.Clause 19. The rotating electric machine according to clause 18, whereinthe rotating electric machine is a motor, and the core of the motorcomprises the pressed powder material.Clause 20. The rotating electric machine according to clause 18, whereinthe rotating electric machine is a generator, and the core of thegenerator comprises the pressed powder material.Clause 21. A plurality of flaky magnetic metal particles, each flakymagnetic metal particle comprising a flat surface; and a magnetic metalphase containing at least one first element selected from the groupconsisting of Fe, Co, and Ni,

the flaky magnetic metal particles having an average thickness ofbetween 10 nm and 100 μm inclusive and an average aspect ratio ofbetween 5 and 10,000 inclusive, and having a difference in coercivity onthe basis of direction within the flat surface.

Clause 22. The flaky magnetic metal particles according to clause 21,wherein the proportion of the difference in coercivity on the basis ofdirection within the flat surface is 1% or higher.Clause 23. The flaky magnetic metal particles according to clause 21 or22, wherein the crystal grain size of the magnetic metal phase is 10 nmor less.Clause 24. The flaky magnetic metal particles according to any ofclauses 21-23, wherein the magnetic metal phase contains at least oneadditive element selected from the group consisting of boron (B),silicon (Si), aluminum (Al), carbon (C), titanium (Ti), zirconium (Zr),hafnium (Hf), niobium (Nb), tantalum (Ta), molybdenum (Mo), chromium(Cr), copper (Cu), tungsten (W), phosphorus (P), nitrogen (N), gallium(Ga), and yttrium (Y).Clause 25. The flaky magnetic metal particles according to any ofclauses 21-24, wherein the flat surface has either or both of aplurality of concavities and a plurality of convexities arranged in afirst direction, each concavity or convexity having a width of 0.1 μm ormore, a length of 1 μm or more, and an aspect ratio of 2 or higher.Clause 26. The flaky magnetic metal particles according to any ofclauses 21-25, wherein the lattice strain of the flaky magnetic metalparticles is between 0.01% and 10% inclusive.Clause 27. The flaky magnetic metal particles according to any ofclauses 21-26, wherein the flaky magnetic metal particles having abody-centered cubic crystal structure.Clause 28. The flaky magnetic metal particles according to any ofclauses 21-27, wherein the flat surface has the (110) plane orientationor the (111) plane orientation.Clause 29. The flaky magnetic metal particles according to any ofclauses 21-28, wherein the ratio of the maximum length with respect tothe minimum length within the flat surface is between 1 and 5 inclusiveon the average, and

each of the flaky magnetic metal particles further comprises a pluralityof small magnetic metal particles on the flat surface, the number of thesmall magnetic metal particles disposed on the flat surface being 5 ormore on the average, and the small magnetic metal particles containingat least one of the first elements and having an average particle sizeof between 10 nm and 1 μm inclusive.

Clause 30. The flaky magnetic metal particles according to any ofclauses 21-29, wherein at least a portion of the surface of the flakymagnetic metal particles is coated with a coating layer having athickness of between 0.1 nm and 1 μm inclusive and containing at leastone second element selected from the group consisting of oxygen (O),carbon (C), nitrogen (N), and fluorine (F).Clause 31. A pressed powder material comprising:

a plurality of flaky magnetic metal particles, each flaky magnetic metalparticle having a flat surface and a magnetic metal phase containing atleast one first element selected from the group consisting of Fe, Co,and Ni, the flaky magnetic metal particles having an average thicknessof between 10 nm and 100 μm inclusive and an average aspect ratio ofbetween 5 and 10,000 inclusive; and

an interposed phase existing between the flaky magnetic metal particlesand containing at least one second element selected from the groupconsisting of oxygen (O), carbon (C), nitrogen (N), and fluorine (F),

the flat surfaces of the flaky magnetic metal particles in the pressedpowder material being oriented parallel to a plane of the pressed powdermaterial, and the pressed powder material having a difference incoercivity on the basis of direction within the plane.

Clause 32. The pressed powder material according to clause 31, whereinthe proportion of the difference in coercivity on the basis of directionwithin the plane of the pressed powder material is 1% or higher.Clause 33. The pressed powder material according to clause 31 or 32,wherein the crystal grain size of the magnetic metal phase is 10 nm orless.Clause 34. The pressed powder material according to any of clauses31-33, wherein the magnetic metal phase contains at least one additiveelement selected from the group consisting of B, Si, Al, C, Ti, Zr, Hf,Nb, Ta, Mo, Cr, Cu, W, P, N, Ga, and Y.Clause 35. The pressed powder material according to any of clauses31-34, wherein the flat surfaces of the flaky magnetic metal particleshave either or both of a plurality of concavities and a plurality ofconvexities arranged in a first direction, each concavity or convexityhaving a width of 0.1 μm or more, a length of 1 μm or more, and anaspect ratio of 2 or higher.Clause 36. The pressed powder material (100) according to any of clauses31-35, wherein the lattice strain of the flaky magnetic metal particlesis between 0.01% and 10% inclusive.Clause 37. The pressed powder material according to any of clauses31-36, wherein the flaky magnetic metal particles have a body-centeredcubic crystal structure.Clause 38. The pressed powder material according to any of clauses31-37, wherein the flat surfaces of the flaky magnetic metal particleshave the (110) plane orientation or the (111) plane orientation.Clause 39. The pressed powder material according to any of clauses31-38, wherein the ratio of the maximum length with respect to theminimum length within the flat surface of a flaky magnetic metalparticle is between 1 and 5 inclusive on the average, and

each of the flaky magnetic metal particles further include a pluralityof small magnetic metal particles on the flat surface, the number of thesmall magnetic metal particles disposed on the flat surface being 5 ormore on the average, and the small magnetic metal particles containingat least one of the first elements and having an average particle sizeof between 10 nm and 1 μm inclusive.

Clause 40. A rotating electric machine comprising the pressed powdermaterial according to any of clauses 31-39.

What is claimed is:
 1. A plurality of flaky magnetic metal particles,each flaky magnetic metal particle comprising a flat surface; and amagnetic metal phase containing at least one first element selected fromthe group consisting of Fe, Co, and Ni, the flaky magnetic metalparticles having an average thickness of between 10 nm and 100 μminclusive and an average aspect ratio of between 5 and 10,000 inclusive,and having a difference in coercivity on the basis of direction withinthe flat surface.
 2. The flaky magnetic metal particles according toclaim 1, wherein the proportion of the difference in coercivity on thebasis of direction within the flat surface is 1% or higher.
 3. The flakymagnetic metal particles according to claim 1, wherein the crystal grainsize of the magnetic metal phase is 10 nm or less.
 4. The flaky magneticmetal particles according to claim 1, wherein the magnetic metal phasecontains at least one additive element selected from the groupconsisting of boron (B), silicon (Si), aluminum (Al), carbon (C),titanium (Ti), zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum(Ta), molybdenum (Mo), chromium (Cr), copper (Cu), tungsten (W),phosphorus (P), nitrogen (N), gallium (Ga), and yttrium (Y).
 5. Theflaky magnetic metal particles according to claim 1, wherein the flatsurface has either or both of a plurality of concavities and a pluralityof convexities arranged in a first direction, each concavity orconvexity having a width of 0.1 μm or more, a length of 1 μm or more,and an aspect ratio of 2 or higher.
 6. The flaky magnetic metalparticles according to claim 1, wherein the lattice strain of the flakymagnetic metal particles is between 0.01% and 10% inclusive.
 7. Theflaky magnetic metal particles according to claim 1, wherein the flakymagnetic metal particles having a body-centered cubic crystal structure.8. The flaky magnetic metal particles according to claim 1, wherein theflat surface has the (110) plane orientation or the (111) planeorientation.
 9. The flaky magnetic metal particles according to claim 1,wherein the ratio of the maximum length with respect to the minimumlength within the flat surface is between 1 and 5 inclusive on theaverage, and each of the flaky magnetic metal particles furthercomprises a plurality of small magnetic metal particles on the flatsurface, the number of the small magnetic metal particles disposed onthe flat surface being 5 or more on the average, and the small magneticmetal particles containing at least one of the first elements and havingan average particle size of between 10 nm and 1 μm inclusive.
 10. Theflaky magnetic metal particles according to claim 1, wherein at least aportion of the surface of the flaky magnetic metal particles is coatedwith a coating layer having a thickness of between 0.1 nm and 1 μminclusive and containing at least one second element selected from thegroup consisting of oxygen (O), carbon (C), nitrogen (N), and fluorine(F).
 11. A pressed powder material comprising: a plurality of flakymagnetic metal particles, each flaky magnetic metal particle having aflat surface and a magnetic metal phase containing at least one firstelement selected from the group consisting of Fe, Co, and Ni, the flaymagnetic metal particles having an average thickness of between 10 nmand 100 μm inclusive and an average aspect ratio of between 5 and 10,000inclusive; and an interposed phase existing between the flaky magneticmetal particles and containing at least one second element selected fromthe group consisting of oxygen (O), carbon (C), nitrogen (N), andfluorine (F), the flat surfaces of the flaky magnetic metal particles inthe pressed powder material being oriented parallel to a plane of thepressed powder material, and the pressed powder material having adifference in coercivity on the basis of direction within the plane. 12.The pressed powder material according to claim 11, wherein theproportion of the difference in coercivity on the basis of directionwithin the plane of the pressed powder material is 1% or higher.
 13. Thepressed powder material according to claim 11, wherein the crystal grainsize of the magnetic metal phase is 10 nm or less.
 14. The pressedpowder material according to claim 11, wherein the magnetic metal phasecontains at least one additive element selected from the groupconsisting of B, Si, Al, C, Ti, Zr, Hf, Nb, Ta, Mo, Cr, Cu, W, P, N, Ga,and Y.
 15. The pressed powder material according to claim 11, whereinthe flat surfaces of the flaky magnetic metal particles have either orboth of a plurality of concavities and a plurality of convexitiesarranged in a first direction, each concavity or convexity having awidth of 0.1 μm or more, a length of 1 μm or more, and an aspect ratioof 2 or higher.
 16. The pressed powder material according to claim 11,wherein the lattice strain of the flaky magnetic metal particles isbetween 0.01% and 10% inclusive.
 17. The pressed powder materialaccording to claim 11, wherein the flaky magnetic metal particles have abody-centered cubic crystal structure.
 18. The pressed powder materialaccording to claim 11, wherein the flat surfaces of the flaky magneticmetal particles have the (110) plane orientation or the (111) planeorientation.
 19. The pressed powder material according to claim 11,wherein the ratio of the maximum length with respect to the minimumlength within the flat surface of a flaky magnetic metal particle isbetween 1 and 5 inclusive on the average, and each of the flaky magneticmetal particles further include a plurality of small magnetic metalparticles on the flat surface, the number of the small magnetic metalparticles disposed on the flat surface being 5 or more on the average,and the small magnetic metal particles containing at least one of thefirst elements and having an average particle size of between 10 nm and1 μm inclusive.
 20. A rotating electric machine comprising the pressedpowder material according to claim 11.